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The Asia-Pacific Journal: Japan Focus
In-depth critical analysis of the forces shaping the Asia-Pacific...and the world.
The Atomic Bombs and the Soviet Invasion: What Drove Japan’s Decision to Surrender?


Almost immediately following the end of World War II, Americans began to question the use of the atomic bomb and the circumstances surrounding the end of the Pacific War. More than half a century later, books and articles on the atomic bomb still provoke storms of debate among readers and the use of atomic weapons remains a sharply contested subject.[1] As the 1995 controversy over the Enola Gay exhibit at the Smithsonian’s National Air and Space Museum revealed, the issues connected with the dropping of the bombs on Hiroshima and Nagasaki continue to touch a sensitive nerve in Americans. Among scholars, disagreement remains no less heated. But, on the whole, this debate has been strangely parochial, centering almost exclusively on how the U.S. leadership made the decision to drop the bombs.

There are two distinct gaps in this historiography. First, with regard to the atomic bombs, as Asada Sadao in Japan correctly observes, American historians have concentrated on the “motives” behind the use of atomic bombs, but “they have slighted the effects of the bomb.”[2] Second, although historians have been aware of the decisive influence of both the atomic bombs and the Soviet entry into the war, they have largely sidestepped the Soviet factor, relegating it to sideshow status.[3]

Two historians, Asada Sadao and Richard Frank, have recently confronted this issue head-on, arguing that the atomic bombing of Hiroshima had a more decisive effect on Japan’s decision to surrender than did Soviet entry into the war.[4] This essay challenges that view. It argues that (1) the atomic bombing of Nagasaki did not have much effect on Japan’s decision; (2) of the two factors—the atomic bombing of Hiroshima and Soviet entry into the war—the Soviet invasion had a more important effect on Japan’s decision to surrender; (3) nevertheless, neither the atomic bombs nor Soviet entry into the war served as “a knock-out punch” that had a direct, decisive, and immediate effect on Japan’s decision to surrender; (4) the most important, immediate cause behind Japan’s decision to surrender were the emperor’s “sacred decision” to do so, engineered by a small group of the Japanese ruling elite; and (5) that in the calculations of this group, Soviet entry into the war provided a more powerful motivation than the atomic bombs to seek the termination of the war by accepting the terms specified in the Potsdam Proclamation. Further, by posing counterfactual hypotheses, I argue that Soviet entry into the war against Japan alone, without the atomic bombs, might have led to Japan’s surrender before November 1, but that the atomic bombs alone, without Soviet entry into the war, would not have accomplished this. Finally, I argue that had U.S. President Harry Truman sought Stalin’s signature on the Potsdam Proclamation, and had Truman included the promise of a constitutional monarchy in the Potsdam Proclamation, as Secretary of War Henry Stimson had originally suggested, the war might have ended sooner, possibly without the atomic bombs being dropped on Japan.

1: The Influence of the Hiroshima Bomb on Japan’s Decision to Surrender

In order to discuss the influence of the atomic bombs on Japan’s decision to surrender, we must examine three separate issues: (1) the effect of the Hiroshima bomb; (2) the effect of the Nagasaki bomb; and (3) the effect of the two bombs combined.
Let us first examine the effect of the Hiroshima bomb. In order to prove that the Hiroshima bomb had a decisive effect on Japan’s decision, Asada and Frank use the following evidence: (1) the August 7 cabinet meeting; (2) the testimony of Lord Keeper of the Privy Seal Kido Koichi concerning the emperor’s statement on August 7; and (3) the emperor’s statement to Foreign Minister Togo Shigenori on August 8.

The atomic bombing of Hiroshima

The Cabinet Meeting on August 7

According to Asada and Frank, the cabinet meeting on August 7 was a crucial turning point. Asada argues that, judging that “the introduction of a new weapon, which had drastically altered the whole military situation, offered the military ample grounds for ending the war,” Foreign Minister Togo Shigenori proposed that “surrender be considered at once on the basis of terms presented in the Potsdam Declaration [Proclamation].”[5] Frank writes: “Togo extracted from the American statements about the ‘new and revolutionary increase in destruct[ive]’ power of the atomic bomb a reason to accept the Potsdam Proclamation.”[6]

If these arguments are correct, there was indeed a fundamental change of policy, at least on the part of Togo, if not the entire cabinet, and the Hiroshima bomb had a decisive effect on Togo’s thinking, since until then he had been advocating suing for peace through Moscow’s mediation before considering the acceptance of the Potsdam Proclamation. In his memoirs, however, Togo does not portray this cabinet meeting as a decisive turning point. The following is all he says about the cabinet meeting: “On the afternoon of the 7th, there was a cabinet meeting. The army minister and the home minister read their reports. The army appeared to minimize the effect of the bomb, without admitting that it was the atomic bomb, insisting that further investigation was necessary.”[7]

The only source that makes a reference to Togo’s insistence on the acceptance of the Potsdam Proclamation was the testimony given by Cabinet Minister Sakomizu Hisatsune under postwar interrogation. Citing Sakomizu’s testimony, Oi Atsushi, who interviewed Togo in preparation for the Tokyo trial, asked him about his alleged proposal to accept the Potsdam terms. Togo replied: “I reported that the United States was broadcasting that the atomic bomb would impart a revolutionary change in warfare, and that unless Japan accepted peace it would drop the bombs on other places. The Army… attempted to minimize its effect, saying that they were not sure if it was the atomic bomb, and that since it [had] dispatched a delegation, it had to wait for its report.”[8] The picture that emerges from this testimony is that Togo merely reported the U.S. message. Perhaps he merely conveyed his preference to consider the Potsdam Proclamation by reporting Truman’s message. But when met with stiff opposition from Army Minister Anami Korechika, who dismissed the American atomic bomb message as mere propaganda, Togo, without a fight, accepted Anami’s proposal to wait until the delegation submitted its official findings. According to Sakomizu’s memoirs, Togo first proposed, and the cabinet agreed, that Japan should register a strong protest through the International Red Cross and the Swiss legation about the American use of the atomic bomb as a serious violation of international law prohibiting poisonous gas. Sakomizu further wrote: “There was an argument advocating the quick termination of war by accepting the Potsdam Proclamation,” but in view of the Army’s opposition, the cabinet merely decided to send the investigation team to Hiroshima.[9]

In other words, neither the cabinet nor Togo himself believed that any change of policy was necessary on the afternoon of August 7, one day after the atomic bomb was dropped on Hiroshima, although the majority of the cabinet members had already known that the bomb was most likely an atomic bomb, and furthermore that unless Japan surrendered, many atomic bombs might be dropped on other cities in Japan. In fact, far from entertaining the possibility of accepting the Potsdam terms, the cabinet was blatantly more combative against the United States, deciding to lodge a formal protest against the use of the atomic bomb.

What Did the Emperor Say on August 7?

The news of the dropping of an atomic bomb on Hiroshima had already been brought to the emperor early in the morning on August 7, but Kido learned of it only at noon. Kido had an unusually long audience with the emperor that lasted from 1:30 to 2:05 in the Imperial Library. Kido’s diary notes: “The emperor expressed his august view on how to deal with the current situation and asked various questions.”[10] But Kido’s diary says nothing about what the emperor’s view was and what questions he asked. Later, Kido recalled that Hirohito had told him: “Now that things have come to this impasse, we must bow to the inevitable. No matter what happens to my safety, we should lose no time in ending the war so as not to have another tragedy like this.”[11] Citing Kido’s account as the decisive evidence, Asada concludes: “The Emperor was… from this time forward Japan’s foremost peace advocate, increasingly articulate and urgent in expressing his wish for peace.”[12] Frank, however, does not share Asada’s description of the emperor as the “foremost peace advocate,” viewing him as wavering at times over whether or not Japan should attach more than one condition to its acceptance of the Potsdam Proclamation.[13]

Kido Koichi

Kido’s description of the emperor’s reaction to the Hiroshima bomb must be taken with a grain of salt. As Hirohito’s closest adviser, Kido worked assiduously to create the myth that the emperor had played a decisive role in ending the war. Kido’s testimony under interrogation on May 17, 1949, was designed to create the image of the benevolent emperor saving the Japanese from further devastation. Hirohito’s offer of “self-sacrifice” does not correspond to his behavior and thinking during those crucial days. It should be noted that on July 30, three days after he received a copy of the Potsdam Proclamation, Hirohito was concerned above all about the safety of the “three divine treasures” (sanshu no jingi) that symbolized the imperial household in Ise Shrine in the event of an enemy attack. Meanwhile, more than 10,000 Japanese were killed by American incendiary bombings during the eleven days from the Potsdam Proclamation to the Hiroshima bomb. Hirohito’s wish to prevent further sacrifice of his “children” (sekishi) at his own risk does not ring true.[14] Contrary to Asada’s assertion, Hirohito’s first and foremost preoccupation was the preservation of the imperial house. Neither does his subsequent behavior indicate that Hirohito was the most persistent, articulate advocate of immediate peace. Here, Frank’s skepticism is closer to the truth than Asada’s conclusion.

The Emperor’s Statement to Togo on August 8

On the following morning, August 8, Foreign Minister Togo Shigenori went to the imperial palace for an audience with the emperor. According to Asada, using the American and British broadcasts “to buttress his case,” Togo urged the emperor to agree to end the war as quickly as possible “on condition, of course, that the emperor system be retained.” Hirohito concurred and replied:

Now that such a new weapon has appeared, it has become less and less possible to continue the war. We must not miss a chance to terminate the war by bargaining [with the Allied powers, Asada adds] for more favorable conditions now. Besides, however much we consult about [surrender, Asada adds] terms we desire, we shall not be able to come to an agreement. So my wish is to make such arrangements as will end the war as soon as possible.[15]

From this statement, Asada concludes that “the emperor expressed his conviction that a speedy surrender was the only feasible way to save Japan.” Hirohito urged Togo to “do [his] utmost to bring about a prompt termination of war,” and told the foreign minister to convey his desire to Prime Minister Suzuki Kantaro. “In compliance with the imperial wish, Togo met Suzuki and proposed that, ‘given the atomic bombing of Hiroshima, the Supreme War Council be convened with all dispatch.’”[16] Frank’s interpretation follows Asada’s basic assumption. According to Frank, “Togo called for immediate termination of the war on the basis of the Potsdam Declaration [Proclamation],” but unlike Asada, he asserts that Hirohito “still balked personally at simple acceptance of the Potsdam Declaration [Proclamation].”[17]

The crucial question here, however, concerns the effect of the Hiroshima bomb on the emperor. Both Asada and Frank make the argument that Togo’s meeting with the emperor was a crucial turning point in both men’s decision to seek an immediate end to the war on the terms stipulated by the Potsdam Proclamation. This argument, however, is not convincing.

“We must not miss a chance to terminate the war by bargaining for more favorable conditions now,” Togo quotes the emperor as saying. Asada adds the words, “with the Allied powers” in brackets after “bargaining,” to read: “We must not miss a chance to terminate the war by bargaining [with the Allied powers] for more favorable conditions now.” Asada takes this to mean that the emperor wished to end the war by accepting the Potsdam Proclamation.[18] Is it correct, however, to interpret the implied meaning here as “bargaining with the Allied powers?” As I argue below, Togo had dispatched an urgent telegram to Japan’s ambassador to the USSR, Sato Naotake, only the previous day, instructing the latter to obtain Moscow’s answer to Prince Konoe Fumimaro’s mission. It is also important to recall that the Japanese government decided to suspend judgment on the Potsdam Proclamation precisely because it had pinned its last hope on Moscow’s mediation. Whom was the Japanese government bargaining with at that moment? Certainly, it was not the Allied powers, as Asada has inserted in brackets. The only party with whom Japan was “bargaining” at that moment was the Soviet Union, not the Allied powers, and the Japanese government preferred to suspend judgment over the Potsdam terms as long as the possibility of Moscow’s mediation still seemed available to it.[19] Hirohito’s statement did not change this position.

Konoe Fumimaro

Before the Hiroshima bombing, Togo had already become convinced that sooner or later, Japan would have to accept the Potsdam terms. It is possible that the Hiroshima bomb further reinforced his conviction. But it bears repeating that he did not take the initiative to reverse the previous course, and that he did not propose direct negotiations with the United States and Britain. As for the emperor, it is possible that the Hiroshima bomb contributed to his urgent desire to terminate the war, but it is erroneous to say that immediately after the Hiroshima bomb, Hirohito decided to accept the Potsdam terms, as Asada asserts.

When Did Suzuki Decide to Terminate the War?

Another piece of evidence on which Asada’s and Frank’s argument is constructed is Prime Minister Suzuki’s statement. According to Asada, on the night of August 8, Suzuki told Sakomizu: “Now that we know it was an atomic bomb that was dropped on Hiroshima, I will give my views on the termination of the war at tomorrow’s Supreme War Council.”[20] After the war, Suzuki made another statement: “The atomic bomb provided an additional reason for surrender as well as an extremely favorable opportunity to commence peace talks.” From these statements, Asada concludes: “The hitherto vacillating and sphinx-like Suzuki had finally made up his mind. It is important to note that Suzuki did so before he was informed of the Soviet entry into the war early on the following day.”[21]

Asada’s conclusion is based on the 1973 version of Sakomizu’s memoirs, according to which, Suzuki called Sakomizu late at night and made the statement quoted by Asada. Sakomizu explains that Suzuki relied on a prepared text written by his secretaries in order to make an official statement. Three pages later, Sakomizu writes: “On Prime Minister Suzuki’s order, I had been working hard to write a text for the prime minister’s statement for the cabinet meeting on the following day since the evening of August 8” (emphasis added). At around one o’clock in the morning on August 9, Hasegawa Saiji of the Domei News Agency telephoned to inform him of the Soviet Union’s entry into the war.[22]

Sakomizu’s 1973 memoirs contain crucial inconsistencies with respect to timing. In his earlier memoirs published in 1964, Sakomizu says that after he informed the prime minister of Dr. Nishina’s report on the Hiroshima atomic bomb, which he had received on the evening of August 8, Suzuki ordered him to call meetings of the Supreme War Council and the cabinet “tomorrow on August 9 so that we can discuss the termination of the war.” It took Sakomizu until 2 A.M. on August 9 to complete the preparations for the meetings on the following day. He finally went to bed thinking about the crucial meeting between Molotov and Sato in Moscow. It was not until three in the morning that Hasegawa called and told him about the Soviet declaration of war on Japan.[23] The timeline described in his 1964 memoirs makes more sense than that in the 1973 memoirs. According to Hasegawa’s testimony, it was not until 4:00 A.M. on August 9 that he telephoned Sakomizu about the Soviet declaration of war, a fact that corresponds to Sakomizu’s account in the 1964 memoirs, but not to that in the 1973 memoirs.[24] Sphinx-like Suzuki, as Asada calls him, had previously confided his views favoring peace privately on numerous occasions, but for domestic morale reasons, he had trumpeted bellicose statements, to the constant chagrin of the foreign minister. The dropping of the atomic bomb reinforced Suzuki’s determination to seek an end to the war, as it did the emperor’s. Nevertheless, it is likely that Suzuki, like everybody else, hoped for Moscow’s mediation to achieve this, as Sakomizu’s 1964 memoirs indicate.[25]

What is important, moreover, is the evidence that Asada chooses to ignore. According to Suzuki’s biography, the prime minister came to the clear conclusion after the Hiroshima bomb that there was no other alternative but to end the war. Nevertheless, it was not until he learned of the Soviet invasion of Manchuria that he “was finally convinced that the moment had at last arrived to end the war, since what we had been afraid of and tried to avoid at any cost had finally come about [kitarubekimono ga kita].” He thought that “now is the time to realize the emperor’s wish,” and “in view of the urgency of the situation, I finally made up my mind to be in charge of the termination of the war, taking all the responsibility upon myself.”[26] This biography makes it clear that Suzuki did not make up his mind about terminating the war until the Soviet entry into the war.[27]

Togo’s Telegram on August 7

That Togo did not change the policy even after the atomic bombing of Hiroshima can be ascertained from important evidence that both Asada and Frank ignore. Right after the cabinet meeting on August 7, Togo dispatched an urgent telegram, no. 993, to Ambassador Sato in Moscow, saying: “The situation is becoming more and more pressing. We must know the Soviets’ attitude immediately. Therefore, do your best once more to obtain their reply immediately.”[28] In the context of the effect of the Hiroshima bomb, this telegram shows that the Japanese government as a whole, and Togo personally, still clung to the hope that the termination of the war was possible and desirable through Moscow’s mediation. This was the line that Togo had followed since the Potsdam Proclamation had been issued by the Allies. The Hiroshima bomb did not change this policy.[29]

Togo Shigenori

The emperor’s statement to Togo, cited by Asada and Frank, can therefore be interpreted as the continuation of, not a departure from, the previous policy. If anything, the Japanese ruling elite pinned their hopes more desperately on Moscow’s mediation after the Hiroshima bomb. There is no evidence to show that the emperor’s words “We must end the war” should be interpreted as “ending the war by accepting the Potsdam Proclamation,” as Asada and Frank argue. When Ambassador Sato cabled to Tokyo that Molotov had finally agreed to see him at 5 P.M. on August 8, no one, including the usually shrewd and hard-nosed Sato himself, doubted that Molotov would give Sato an answer to Japan’s long-standing request that Moscow receive Prince Konoe as the emperor’s special envoy.

There is no evidence to indicate that the Hiroshima bomb immediately and directly induced either the Japanese government as a whole or individual members, including Togo, Suzuki, Kido, and Hirohito, to terminate the war by accepting the terms of the Potsdam Proclamation. Japan could wait until Moscow’s reaction before it would decide on the Potsdam terms.

Measuring the Shock Value

Asada argues that the atomic bombs provided a greater shock to Japanese policymakers than the Soviet entry into the war because (1) the bombing was a direct attack on the Japanese homeland, compared with the Soviet Union’s “indirect” invasion in Manchuria; and (2) it was not anticipated. As for the first argument, the comparison between atomic bombings of the homeland and the Soviet invasion in Manchuria is irrelevant. American conventional air attacks had had little effect on Japan’s resolve to fight the war. What separated the conventional attacks and the atomic bombs was only the magnitude of the one bomb, and it is known that the cumulative effects of the conventional attacks by American air raids caused more devastation in terms of the number of deaths and destruction of industries, ports, and railroads. But the number of sacrifices was not the major issue for Japanese policymakers.

The hierarchy of values under which the Japanese ruling elite operated is crucial in understanding the psychological factor involved in evaluating the effect of the atomic bombs on Japan’s decision to surrender. The number of victims and profound damage that the atomic bombs inflicted on the citizens of Hiroshima and Nagasaki, which the American policymakers had hoped would have a decisive influence on the Japanese government, were not among the top considerations of the Japanese ruling elite. The Japanese policymakers, from the emperor down to the military and civilian leaders, including Togo himself, were prepared to sacrifice the lives of millions more Japanese to maintain the kokutai (national polity), however they interpreted this nebulous concept. If the effects of the bombs caused concern for the ruling elite—especially to Hirohito, Kido, Konoe, and others closest to the emperor—it was because the devastation caused by the bombs might lead to a popular revolt that could sweep away the emperor system.

If the degree of shock can be measured by the action taken in response to the event, one might argue that the Hiroshima bomb did not have a greater effect than Soviet entry into the war, since no one, including Hirohito, Kido, Suzuki, and Togo, took any concrete actions to respond to the Hiroshima bomb. The Supreme War Council was not even convened for three full days after the Hiroshima bomb; not until after the USSR entered the war against Japan did it meet. It is true that the emperor instructed Suzuki to convene the Supreme War Council, and Sakomizu attempted to hold the meeting on Suzuki’s orders. But “because some military leaders had prior commitments,” he could not arrange the meeting until the morning of August 9. Asada considers this delay “criminal,” but this laxity is indicative of the way the ruling elite felt regarding the “shock” of the Hiroshima bomb.

The Supreme War Council that was convened on the morning of August 9 immediately after the Soviet invasion of Manchuria was not the same meeting that Sakomizu had arranged on the previous night. The formality of the Supreme War Council meeting required a new summons in order to convene.[30] Sakomizu’s previous arrangements made it easier to summon the new meeting, but the speed with which the Supreme War Council was convened indicates the urgency that the Japanese government felt about the situation immediately after the Soviet invasion of Manchuria. Such urgency was absent in its reaction to the Hiroshima bombing. On August 10 and on August 14, Hirohito summoned the imperial conference on his own initiative. It was within his power to do so, but no one believed this was called for immediately after the Hiroshima bombing.

Finally, in his telegram to Sato on August 7, Togo described the situation as “becoming more and more pressing,” but not completely desperate. The Hiroshima bomb did not make the Japanese ruling elite feel as though their backs were to the wall. It inflicted a serious body blow, but it was hardly a knock-out punch.

2. The Influence of the Nagasaki Bomb and of the Two Atomic Bombs Combined

Chronologically, the Soviet entry into the war was sandwiched between the Hiroshima bomb and the Nagasaki bomb. But here, reversing the chronological order, I shall discuss the effect of the Nagasaki bomb first.

The news of the Nagasaki bomb was reported to Japanese leadership during the middle of a heated discussion at the Supreme War Council after the Soviet invasion, but this news had no effect on the discussion. Asada concedes that “[the] strategic value of a second bomb was minimal,” but says that “from the standpoint of its shock effect, the political impact of [the] Nagasaki bomb cannot be denied.” He explains that Suzuki now began to fear that “the United States, instead of staging the invasion of Japan, will keep on dropping atomic bombs.” Asada therefore concludes that the Nagasaki bomb was “unnecessary to induce Japan to surrender, but it probably had confirmatory effects.”[31] It is true that Suzuki said at the cabinet meeting on the afternoon of August 13 that the atomic bombs nullified the traditional form of homeland defense. But it appears that the military treated the Nagasaki bomb as a part of the ordinary incendiary air raids. Even after the Nagasaki bomb, and even though Anami made startling assertions that the United States might possess more than 100 atomic bombs, and that the next target might be Tokyo, the military insisted upon the continuation of the Ketsu Go strategy. Anami’s revelation did not seem to have any effect on the positions that each camp had held. The Nagasaki bomb simply did not substantially change the arguments of either side. The official history of the Imperial General Headquarters notes: “There is no record in other materials that treated the effect [of the Nagasaki bomb] seriously.”[32]

Nagasaki following the atomic bombing

Thus, it is fair to conclude that the Nagasaki bomb and, for that matter, the two bombs combined, did not have a decisive influence on Japan’s decision to surrender. Remove the Nagasaki bomb, and Japan’s decision would have been the same.

3. The Influence of the Soviet Entry into the War

According to Asada, of the atomic bombs and the Soviet entry into the war, the atomic bombings of Hiroshima and Nagasaki gave Japanese leaders the greater shock. He argues:

From the viewpoint of the shock effect, then, it may be argued that the bomb had a greater impact on Japanese leaders than did the Soviet entry into the war. After all, the Soviet invasion of Manchuria gave them an indirect shock, whereas the use of the atomic bomb on their homeland gave them the direct threat of the atomic extinction of the Japanese people.
The shock of the bomb was all the greater because it came as a “surprise attack.”[33]

Frank also asserts: “the Soviet intervention was a significant but not decisive reason for Japan’s surrender. It was, at best, a reinforcing but not fundamental reason for the intervention by the Emperor.”[34]

The Japanese General Staff’s Assessment of the Soviet Threat

Asada’s assumption that since the Japanese military had anticipated the Soviet attack, it was not a shock to them when it really happened is questionable. The Japanese military began reassessing the Soviet threat even before Germany surrendered in May. On June 8, the imperial conference adopted the document “The Assessment of the World Situation,” prepared by the General Staff. This assessment judged that after the German capitulation, the Soviet Union would plan to expand its influence in East Asia, especially in Manchuria and China, when an opportunity arose. The USSR had taken a series of measures against Japan, it continued, to prepare to enter into hostile diplomatic relations, while reinforcing its troops in the east. Therefore, when Moscow judged that the military situation had become extremely disadvantageous to Japan and that its own sacrifice would be small, the document concluded, there was a great probability that the Soviet Union might decide to enter the war against Japan. It predicted that in view of the American military plan, the climatic conditions in Manchuria, and the rate of the military buildup in the Soviet Far East, an attack might come in the summer or the fall of 1945.[35] The General Staff further paid close attention to the rate of Soviet reinforcement of troops and equipment in the Far East. By the end of June, the USSR had already sent troops, weapons, airplanes, tanks, and other equipment far surpassing the level that had existed there in 1941. The General Staff concluded that if this pace were kept up, the Soviet military would reach a preparedness level sufficient to go to war against Japan by August.[36]

In the beginning of July, the General Staff refined this assessment and came to the conclusion that the USSR might likely launch large-scale operations against Japan after February 1946, while the initial action to prepare for this operation in Manchuria might take place in September 1945. This assessment concluded: “It is unlikely that the Soviet Union will initiate military action against Japan this year, but extreme vigilance is required over their activities in August and September.”[37] Thus, the General Staff thought that a Soviet attack might be possible, but what dominated its thinking was the hope that it could be avoided. On the basis of this wishful thinking, the General Staff did not prepare the Kwantung Army for a possible Soviet invasion. In fact, despite the General Staff’s assessment that the Soviet attack might occur in August–September, the military preparedness of the Kwantung Army was such that had an attack occurred in August–September, it would not have had any possibility of defending itself.[38]

The General Staff was not unanimous in its assessment of Soviet intentions. The Fifth Division of the Strategy Guidance Department of the General Staff was in charge of intelligence regarding the Soviet Army, and it was the conclusions of this division that resulted in the portion of the General Staff’s assessment that predicted the possibility of a Soviet attack in August–September. The assessment of the Fifth Division met opposition from the Twelfth Division (War Guidance Division), headed by Colonel Tanemura Suetaka. Tanemura was one of the staunch advocates who insisted upon the need to keep the Soviet Union neutral. At one meeting at the end of July, Tanemura strenuously objected to Colonel Shiraki Suenari’s assessment that the Soviet attack might come as early as August 10. Tanemura assailed this assessment, stating: “This assessment overexaggerates the danger. Stalin is not so stupid as to attack Japan hastily. He will wait until Japan’s power and military become weakened, and after the American landing on the homeland begins.” Since the Twelfth Division was closely connected with the Bureau of Military Affairs, the nerve center of the General Staff, Tanemura’s view became the prevailing policy of the General Staff, and hence of the Army as a whole.[39]

On August 8, one day before the Soviet invasion, the General Staff’s Bureau of Military Affairs produced a study outlining what Japan should do if the Soviet Union issued an ultimatum demanding Japan’s total withdrawal from the Asian continent. According to this plan, the following alternatives were suggested: (1) reject the Soviet demand and carry out the war against the Soviet Union in addition to the United States and Britain; (2) conclude peace with the United States and Britain immediately and concentrate on the war against the Soviet Union; (3) accept the Soviet demand and seek Moscow’s neutrality, while carrying on the war against the United States and Britain; and (4) accept the Soviet demand and involve the Soviet Union in the Greater East Asian War. Of these alternatives, the army preferred to accept the Soviet demand and either keep the Soviet Union neutral or, if possible, involve the Soviet Union in the war against the United States and Britain.[40]

The Bureau of Military Affairs also drafted a policy statement for the Supreme War Council in the event that the Soviet Union decided to participate in the war against Japan. In that case, it envisioned the following policy: (1) fight only in self-defense, without declaring war on the Soviet Union; (2) continue negotiations with the Soviet Union to terminate the war, with the minimal conditions of the preservation of the kokutai and the maintenance of national independence; (3) issue an imperial rescript appealing to the people to maintain the Yamato race; and (4) establish a martial law regime.[41] In a document presented to the Supreme War Council, the army recommended that if the Soviet Union entered the war, Japan should “strive to terminate the war with the Soviet Union as quickly as possible, and to continue the war against the United States, Britain, and China, while maintaining Soviet neutrality.”[42] In his postwar testimony, Major-General Hata Hikosaburo, the Kwantung Army’s chief of staff, recalled that the Kwantung Army had believed that it could count on Soviet neutrality until the spring of the following year, although it allowed for the slight chance of a Soviet attack in the fall.[43]

It bears emphasizing that right up to the moment of invasion, the army not only did not expect an immediate Soviet invasion but also it still believed that it could either maintain Soviet neutrality or involve the Soviet Union in the war against the United States and Britain. The thinking that dominated the center of the army and the Kwantung Army was indeed “wishful thinking,” that a Soviet attack, although possible, would not happen.[44]

Thus, it is misleading to conclude, as Asada does, that since the army had assessed that the Soviet attack might take place, the Soviet invasion into Manchuria was not a shock to the Japanese military. The Bureau of Military Affairs suppressed the prediction that a Soviet attack was imminent and relied instead on its wishful thinking that it could be avoided. Its strategy was based on this assessment. Therefore, when Soviet tanks crossed the Manchurian border, the news certainly was a great shock to it, contrary to Asada’s assertion.

Deputy Chief of Staff Kawabe’s Attitude

To support his assertion that the Soviet invasion had little effect on the Japanese military’s will to fight, Asada cites the following passage from Deputy Chief of Staff Kawabe Torashiro’s diary entry from the crucial day, August 9, 1945: “To save the honor of the Yamato race, there is no way but to keep on fighting. At this critical moment, I don’t even want to consider peace or surrender.”[45] But if we examine Kawabe’s diary more closely, a slightly different picture emerges.

Kawabe Torashiro

Kawabe was awakened in bed at the General Staff headquarters at around 6:00 A.M., and he received the news from his aide that the Intelligence Division had intercepted broadcasts from Moscow and San Francisco reporting that the Soviet Union had declared war on Japan. Kawabe wrote down his first impressions of the news as follows:

The Soviets have finally risen! [So wa tsuini tachitari!] My judgment has proven wrong. But now that the situation has come to this, we should not consider seeking peace. We had half anticipated this military situation and the military fortune. There is nothing to think about. To save the honor of the Yamato race, there is no other way but to keep fighting. When we decided to begin the war, I always belonged to the soft and prudent faction, but once the situation has come to this, I don’t like to think about peace and surrender. Whatever the outcome, we have no choice but to try.[46]

Asada is correct in pointing out that despite the news of the Soviet invasion in Manchuria, Kawabe was determined to continue the war. And yet Kawabe’s diary also betrays the shock and confusion he felt at the news. Contrary to his “judgment,” Kawabe conceded, “the Soviets have risen!” This exclamation mark speaks volumes about Kawabe’s shock. In fact, until then all Ketsu Go strategy had been built upon the assumption that the USSR should be kept neutral, and for that reason Kawabe himself had campaigned hard for the Foreign Ministry to secure Soviet neutrality through negotiations. He admitted that his judgment had proved wrong. But this admission was immediately followed by a Monday morning quarterback–like reflection that the eventuality of a Soviet attack had been in the back of his mind. This is not necessarily a contradiction. In fact, Kawabe and the Army General Staff had been bothered by the nagging suspicion that the Soviets might strike at Japan. This suspicion, however, prompted the army to double its efforts to secure Soviet neutrality. Moreover, the army did not anticipate, first, that the attack was to come so soon, at the beginning of August, and second, that the Soviet invasion would take place on such a large scale against the Japanese forces in Manchuria and Korea from all directions.

Kawabe’s diary also reveals his confusion. If his judgment proved wrong, logically it should follow that the strategy that he had advocated based on the erroneous assumption should have been reexamined. Instead of adopting this logical deduction, Kawabe “did not feel like peace and surrender in this situation.” This was not rational strategic thinking, but a visceral reluctance to accept surrender. The only rationale he could justify for the continuation of war was “the honor of the Yamato race.” His insistence on fighting was also a preemptive move, anticipating, quite correctly, that the peace party would launch a coordinated move to end the war. Nevertheless, his argument for the continuation of war indicated the degree of the army’s desperation and confusion.

If the Soviet invasion indeed shocked the military, which event, the atomic bombing of Hiroshima or the Soviet attack, provided a bigger shock? In order to answer this question, one must compare the August 9 entry with the August 7 entry in Kawabe’s diary. In the entry for August 7, Kawabe wrote: “As soon as I went to the office, having read various reports on the air raid by the new weapon on Hiroshima yesterday morning of the 6th, I was seriously disturbed [shinkokunaru shigeki o uketari, literally, ‘received a serious stimulus’] With this development [kakutewa] the military situation has progressed to such a point that it has become more and more difficult. We must be tenacious and fight on.”[47] Kawabe admitted that he was disturbed by, or more literally, received “a serious stimulus [shigeki]” from the reports of the atomic bomb at Hiroshima. Nevertheless, he avoided using the term “shogeki [shock].” Compared with this passage describing the news of the atomic bomb as a matter of fact, the first thing that catches the eye in his entry for August 9 is the first sentence, “So wa tsuini tachitari!” (“The Soviets have finally risen!”). As far as Kawabe was concerned, there is no question but that the news of the Soviet attack gave him a much bigger shock than the news of the atomic bomb.

Both diary entries advocated continuing the war. But there was a subtle change. While the effects of the atomic bomb were described as having worsened the military situation, there was no change in the overall assumptions. But Kawabe’s insistence on fighting after the Soviet attack is marked by his defensive tone, deriving partly from the anticipated move for peace and partly from the disappearance of the fundamental assumptions on which the continuation of the war had rested. In this respect, too, the shock of the Soviet attack was much greater to the military than the atomic bombing of Hiroshima.
Kawabe’s August 9 diary entry goes on to describe the subsequent events at General Staff headquarters. He recorded his decisions in an elliptical memorandum that singles out the continuation of war against the United States as the major task, and suggests the following measures: (1) proclaim martial law, dismiss the current cabinet, and form a military dictatorship; (2) abandon Manchuria, defend Korea, and dispatch troops from northern China to the Manchurian-Korean border; (3) evacuate the Manchurian emperor to Japan; and (4) issue a proclamation in the name of the army minister to avoid disturbances (doyo) within the military. Thus, in Kawabe’s mind, the continuation of war was associated with the establishment of a military dictatorship in order to forestall the movement to end the war that would inevitably gather momentum as Soviet tanks penetrated deep into Manchuria.

Kawabe’s diary entry for the evening of August 9 also indicates his psychological condition. Unable to sleep because of mosquitoes and Tokyo’s tropical heat, he mused on the fate of the country: “To continue fighting will mean death, but to make peace with the enemy will mean ruin. But we have no choice but to seek life in death with the determination to have the entire Japanese people perish with the homeland as their deathbed pillow by continuing to fight, thereby keeping the pride of the Yamato race forever.”[48]

Insisting on the continuation of the war clearly lacked all strategic rationale.
Kawabe’s determination to fight, however, easily collapsed as soon as the emperor’s “sacred decision” was made at the imperial conference on August 10. After he was informed of the result of the imperial conference, he noted in his diary: “Alas, everything is over.” He was critical of the argument advanced by Anami, Umezu, and Toyoda, because he did not believe the conditions they had insisted upon would be accepted by the enemy. For Kawabe, there were only two options: either accept unconditional surrender or perish to maintain honor. The emperor’s decision revealed that he had completely lost his trust in the military. In Kawabe’s view, this was not merely the emperor’s opinion, but the expression of the general view broadly shared by the Japanese people as a whole. Kawabe continues:

How is it that not one military officer from the army and the navy before the emperor could assure [him] that we would be able to win the war? …How ambiguous the answer of the two chiefs was: “Although we cannot say that we shall be able to win the war definitely, we have no reason to believe that we shall definitely lose the war.” No, I am not criticizing their answer. Their answer reflects reality. Although I have persistently insisted on the continuation of war and have encouraged myself to continue fighting, I would have no choice but to give the same answer as given by the chiefs if I were to be asked about the probability of our victory. I am only driven by the sentiment that “I don’t want to surrender; I don’t want to say surrender even if I am killed,” and wish to limit the conditions for the termination of the war.

Kawabe further noted that the General Staff officers knew more than anyone else about the difficulty of continuing the war.[49]

In November 1949, Kawabe gave this testimony in response to point-blank questions : “[B]etween the atomic bombing and the entry of Soviet Russia into the war, which of the two factors played a greater part in bringing about the cessation of hostilities?” the U.S. GHQ interrogator, Oi Atsushi, asked. Kawabe replied:

When the atomic bomb was dropped, I felt: “This is terrible.” Immediately thereafter, it was reported Soviet Russia entered the war. This made me feel: “This has really become a very difficult situation.”
Russia’s participation in the war had long since been expected, but this does not mean that we had been well prepared for it. It was with a nervous heart filled with fear that we expected Russia to enter the war. Although it was a reaction of a man who was faced with the actual occurrence of the inevitable, mine was, to speak more exact, a feeling that “what has been most [feared] has finally come into reality.” I felt as though I had been given a thorough beating in rapid succession, and my thoughts were, “So not only has there been an atomic bombing, but this has come, too.”

I believe that I was more strongly impressed with the atomic bomb than other people. However, even then, … because I had a considerable amount of knowledge on the subject of atomic bombs, I had an idea that even the Americans could not produce so many of them. Moreover, since Tokyo was not directly affected by the bombing, the full force of the shock was not felt. On top of it, we had become accustomed to bombings due to frequent raids by B-29s.

Actually, [the] majority in the army did not realize at first that what had been dropped was an atomic bomb, and they were not generally familiar with the terrible nature of the atomic bomb. It was only in a gradual manner that the horrible wreckage which had been made of Hiroshima became known, instead of in a manner of a shocking effect.

In comparison, the Soviet entry into the war was a great shock when it actually came. Reports reaching Tokyo described Russian forces as “invading in swarms.” It gave us all the more severe shock and alarm because we had been in constant fear of it with a vivid imagination that “the vast Red Army forces in Europe were now being turned against us.” In other words, since the atomic bomb and the Russian declaration of war were shocks in a quick succession, I cannot give a definite answer as to which of the two factors was more decisive in ending hostilities.[50]

Kawabe’s testimony repudiates Asada’s contention that since it was anticipated, the Soviet attack did not represent a shock to the military. Moreover, up to the last sentence, Kawabe’s argument reinforces the view that the Soviet entry into the war had a greater effect on the military than the atomic bomb.
Frank dismisses this statement by arguing that the emperor’s decision to surrender was made even before the accurate assessment of the Manchurian situation reached Tokyo.[51] This is hardly a convincing argument. The effect of the Soviet entry had little relation to the military situation in Manchuria. The very fact that the USSR had entered the war shattered Japan’s last hope for ending it through Soviet mediation. In other words, the political consequence of the Soviet action, not the military situation in Manchuria, was the crucial factor.

Other Testimonies by Military Leaders

A document in Arisue Kikan News no. 333, which gave the Army Ministry’s answer to the prepared questions of the GHQ, provides interesting information. To the question of whether or not the army knew that sooner or later the Soviet Union would join the war with the Allies against Japan, the Army Ministry answered that it had had no knowledge of this. The army had tried to prevent the Soviet Union from participating in the war, because it had believed that Soviet participation would have a great political and strategic effect on major operations against Japan’s main enemy, the United States. Japan was prepared to give up Manchuria in order to keep the USSR out of the war. To the question of whether or not Japan would have accepted surrender before the Soviet entry into the war, this document answers: “The Soviet participation in the war had the most direct impact on Japan’s decision to surrender.”[52]

Major-General Amano Masakazu, the operations department chief at Imperial General Headquarters, replied this way to GHQ interrogation regarding the effect of Soviet entry into the war: “It was estimated that the Soviet Union would most likely enter the war in early autumn. However, had the Soviet Union entered the war, the Imperial General Headquarters had no definite plan to resist the Soviet Union for a long period while effectively carrying out a decisive battle with the American forces on the other. There was nothing to be done but hope that … the 17th Area Army [of the Kwantung Army], reinforced by crack units from the China area, would do their best and would be able to hold out as long as possible.”[53] Amano confessed that the army had possessed no way to counter a Soviet attack, although it thought that this might come in early autumn. It is difficult then to argue from Amano’s statement, as Asada does, that simply because it had been anticipated, the Soviet attack was not a great surprise to the army.

Lieutenant-General Ikeda Sumihisa, director of the General Planning Agency, testified that “upon hearing of the Soviet entry into the war, I felt that our chances were gone.” Having served in the Kwantung Army, he knew its condition well. The Kwantung Army was no more than a hollow shell, largely because it had been transferring its troops, equipment, and munitions to the home islands since the latter part of 1944 in anticipation of the homeland defense. Ikeda often told the commander of the Kwantung Army “that if the USSR entered the war, Japan would never be able to continue the war.” He firmly believed that “in the event that the Soviet [Union] entered the war, Japan’s defeat would be a foregone conclusion.”[54]

Colonel Hayashi Saburo, Anami’s secretary, was asked by a GHQ interrogator about the influence of the atomic bombs and the Soviet entry into the war on Anami’s views regarding the termination of the war. Hayashi did not say anything about the effect of the atomic bomb, but he was confident that the Soviet entry into the war reinforced Anami’s feelings about the need to hasten the end of the war.[55]

Chief of the Navy General Staff Admiral Toyoda Soemu also gave revealing testimony to the GHQ interrogators. He admitted that the atomic bomb had been a shock, but he believed that the United States would not be able to continue to drop atomic bombs “at frequent intervals,” partly because of the difficulty of securing radioactive materials, and partly because of world public opinion against such an atrocity. “I believe the atomic bombing was a cause for the surrender,” Toyoda testified, “but it was not the only cause.” In contrast to the atomic bombs, the Soviet entry into the war was a greater shock to the military. “In the face of this new development,” Toyoda continued, “it became impossible for us to map any reasonable operation plan. Moreover, the peace program which we had so far relied upon [i.e., through Moscow’s mediation] came to naught. Therefore, an entirely different program had to be sought out. At the same time we could not expect to obtain a good chance for peace by merely waiting for such a chance. It was time for us to accept the terms of the Potsdam Declaration [Proclamation].” Toyoda concluded: “I believe the Russian participation in the war against Japan rather than the atomic bombs did more to hasten the surrender.”[56]

Asada ignores all this overwhelming evidence that stresses the importance of the Soviet entry into the war. In the face of this evidence, his contention that because the military had expected the Soviet invasion, it did not shock them when it actually happened cannot be sustained.

Frank casts doubt on the reliability of Kawabe’s and Toyoda’s testimonies because they were given some years after the events. Although he does not quote from Ikeda and Hayashi, he would likely discount them on the same grounds. Frank’s methodology of separating contemporaneous sources from evidence that came after the events is commendable. One cannot apply this method too rigidly, however. In the first place, what benefits did Kawabe, Toyoda, Ikeda, and Hayashi gain by emphasizing the Soviet factor rather than the atomic bomb years after the events? One may even argue that their statements carry more weight because they were made to American interrogators, who had a vested interest in proving that the atomic bombs were more decisive than the Soviet entry.
After dismissing Kawabe’s and Toyoda’s recollections years after the events, Frank extensively quotes from Suzuki’s testimony in December 1945:

The Supreme War Council, up to the time [that] the atomic bomb was dropped, did not believe that Japan could be beaten by air attack alone. They also believed that the United States would land and not attempt to bomb Japan out of the war. On the other hand there were many prominent people who did believe that the United States could win the war by just bombing alone. However, the Supreme War Council, not believing that, had proceeded with the one plan of fighting a decisive battle at the landing point and was making every possible preparation to meet such a landing. They proceeded with that plan until the atomic bomb was dropped, after which they believed the United States would no longer attempt to land when it had such a superior weapon … so at that point they decided that it would be best to sue for peace.[57]

Relying on Suzuki’s statement, Frank concludes: “Suzuki’s assessment goes to the heart of the matter: Soviet intervention did not invalidate the Ketsu-Go military and political strategy; the Imperial Army had already written off Manchuria.”[58] But this statement cannot persuasively prove that Suzuki had already decided to seek the termination of the war according to the Potsdam terms before the Soviet invasion. It must be kept in mind that these testimonies are English translations of the original Japanese statements. When Suzuki referred to the “atomic bomb,” he must have used the term, genbaku or genshi bakudan. A peculiarity of the Japanese language is that it makes no distinction between a singular and a plural noun. Therefore, when Suzuki said genbaku, he was likely referring to the atomic bombs, meaning the bomb at Hiroshima and the bomb at Nagasaki. In fact, it is better to interpret these terms as referring to the plural form. Taken as such, what Suzuki meant must have been the effect of the two bombs in a general sense. Therefore, it is erroneous to conclude, as Asada and Frank do, that Suzuki’s decision to end the war predated the Soviet attack on Japan, since Suzuki was comparing the atomic bombs with conventional air attacks, not with Soviet entry into the war.[59]
Furthermore, although Suzuki may have believed that the atomic bombs had nullified the basic assumption on which the Ketsu Go strategy was based, his view was not necessarily shared by the Army officers. Anami consistently argued throughout the critical days even after the Hiroshima and Nagasaki bombs that the army was confident it could inflict tremendous damage on the invading American troops, indicating that Anami and the army officers continued to believe that despite the atomic bombs, the Americans still planned to launch a homeland invasion. And this assessment was fundamentally correct, since American military planners never substituted atomic bombing alone for the plan to invade Japan.

In fact, as the Bureau of Military Affairs report to the Diet in September 1945 indicated, army planners rejected the “counterforce” effects of atomic weapons in a battleground situation. It states: “It is true that the appearance of the atomic bomb brought a great psychological threat, but since its use would be extremely difficult on the battleground, in view of the close proximity of the two forces and scattered units, we were convinced that it would not directly affect our preparations for homeland defense.”[60] Toyoda’s testimony, quoted above, also questioned the American intention to rely on the atomic bombs. When it came down to the military plan, it was not Suzuki’s view, but the views of the Army and Navy General Staff that mattered most.

As for Soviet entry into the war, the report of the Bureau of Military Affairs states: “Although the Soviet participation in the war was expected from the analysis of the general world situation, we did not anticipate the situation where we would have to fight on the two fronts from the point of view of the nation’s total power. Throughout we had decided to focus our major strategy on the homeland defense, while preparing to sacrifice the operations in the continental defense. Therefore, Soviet entry into the war did not directly affect our conviction that we would score victory in the decisive homeland battle.”[61] This is an ambiguous and contradictory statement. On the one hand, it states that Soviet participation in the war was unexpected, forcing Japan to fight on two fronts. On the other, it takes the view that the Ketsu Go strategy had already written off Manchuria, which did not substantially affect homeland defense. The latter conclusion seems to support Frank’s argument that since the Japanese Army had already written off Manchuria, Soviet entry into the war did not substantially change the army’s strategy of putting all its eggs in the one basket of the Ketsu Go strategy. The problem with this argument is that it ignores the assertion that Japan did not anticipate having to fight on two fronts.
To be fair to the arguments advanced by Asada and Frank, Imperial General Headquarters anticipated the possibility of Soviet participation in the war and adopted a strategy to cope with this worse-case scenario. Already in September 1944, Imperial General Headquarters summoned the Kwantung Army’s operational chief, Colonel Kusachi Sadakichi, and issued Continental Order 1130, by which it ordered the Kwantung Army to concentrate on the defense of a small strip of Manchukuo and Korea against Soviet attack with the strict orders not to provoke any military confrontations with the Red Army.[62] The Kwantung Army mapped out the final operational plan against the Soviet attack on July 5, which basically followed Continental Order 1130.[63] As for Hokkaido, Imperial General Headquarters issued Continental Order 1326 on May 9, 1945, which defined the task of the Fifth Area Army in Hokkaido as the defense of Hokkaido itself. For this purpose, the Fifth Area Army was ordered to direct the defense of southern Sakhalin primarily against the possible Soviet attack, while blocking a U.S. and Soviet landing on the Kurils and crossing the Soya Straits. As for the possible Soviet invasion of Hokkaido, the Fifth Area Army was “to attempt to repulse the enemy depending on circumstances and points of attack and to secure important areas of Hokkaido.”[64]

Alongside with these military plans, however, Imperial General Headquarters harbored wishful thinking that there was unlikely to be a Soviet attack. The Kwantung Army had little confidence in its ability to hold the last defense line. As for the Fifth Area Army, it expected that in the event of the anticipated American invasion of the homeland, Hokkaido would be left to defend itself against a possible combined attack by the United States and the Soviet Union. The problem with Hokkaido’s defense was its size, which was as big as the whole of Tohoku and Niigata prefectures combined. The Fifth Area Army had to disperse 114,000 troops to three possible points of attack: one division in the Shiribetsu-Nemuro area in the east, one division at Cape Soya in the north, and one brigade in the Tomakomai area in the west. The fortification of the Shibetsu area had not been completed, and the defense of the Nemuro area was considered hopeless because of the flat terrain. The defense of the north was concentrated at Cape Soya, but nothing was prepared for Rumoi, where the Soviet forces intended to land.[65] The inadequacies of these operational plans, both in the Kwantung Army and the Fifth Area Army, were exposed when the actual Soviet attack came. The military planners had no confidence in the army’s ability to repulse a Soviet invasion of Korea and Hokkaido. As Frank writes, “the Soviet Navy’s amphibious shipping resources were limited but sufficient to transport the three assault divisions in several echelon[s]. The Red Army intended to seize the northern half of Hokkaido. If resistance proved strong, reinforcements would be deployed to aid the capture the rest of Hokkaido. Given the size of Hokkaido, the Japanese would have been hard pressed to move units for a concerted confrontation of the Soviet invasion. The chances of Soviet success appeared to be very good.”[66] Soviet occupation of Hokkaido was thus within the realm of possibility.

4. The Soviet Factor in the Emperor’s “Sacred Decision”

Although Soviet entry into the war played a more decisive role in Japan’s decision to surrender, it did not provide a “knock-out punch” either. The Supreme War Council and the cabinet found themselves confronted by a stalemate between those who favored acceptance of the Potsdam terms with one condition, the preservation of the imperial house, and those who insisted in addition that there be no Allied occupation and that demilitarization and any war crimes trials be conducted by Japan itself. Given the political weight of the army and an overwhelming sentiment among army officers in favor of continuing the war, the war party might have prevailed had there not been a concerted effort to impose peace on the reluctant army by imperial fiat. Togo, Prince Konoe, and Shigemitsu were instrumental in persuading the wavering Kido and Hirohito, but more important were second-echelon players such as Sakomizu (Suzuki’s cabinet secretary), Deputy Foreign Minister Matsumoto Shun’ichi, Colonel Matsutani Makoto (Suzuki’s secretary and crucial liaison with the army), Matsudaira Yasumasa (Kido’s secretary), and Rear Admiral Takagi Sokichi (Navy Minister Yonai’s closest confidant).[67] Throughout this complicated political process, in which the emperor intervened twice to impose his “sacred decision” to accept the Potsdam terms, first with one condition and the second time unconditionally, the Soviet factor, more than the atomic bombs, played the decisive role.

Political Calculations

Soviet entry into the war was indeed a shock to the Japanese ruling elite, both civilian and military alike. Politically and diplomatically, it dashed any hope of ending the war through Soviet mediation. But Soviet entry meant more than merely precluding the option of Soviet mediation for peace. Here, we must consider the political calculations and psychological factors apparent in dealing with Japan’s two enemies. Before the invasion of Manchuria, the Soviet Union had been Japan’s best hope for peace, while the Japanese ruling elite felt bitter resentment toward the United States, which had demanded unconditional surrender. After August 9, this relationship was reversed. The small opening that the United States had intentionally left ajar in the Potsdam terms, which Japanese foreign ministry officials had astutely noticed as soon as the Potsdam Proclamation was issued, suddenly looked inviting, providing the only room in which the Japanese could maneuver. They concluded that suing for peace with the United States would confer a better chance of preserving the imperial house, if not the kokutai as it was envisaged by ultranationalists. No sooner had the marriage of convenience uniting right-wing Japan and the communist Soviet Union broken down than the Japanese ruling elite’s fear of communism sweeping away the emperor system was reawakened. To preserve the imperial house, it would be better to surrender before the USSR was able to dictate terms. On August 13, rejecting Anami’s request that the decision to accept U.S. Secretary of State James Byrnes’s counteroffer (the “Byrnes note”), which rejected Japan’s conditional acceptance of the Potsdal terms, be postponed, Suzuki explained: “If we miss today, the Soviet Union would take not only Manchuria, Korea, [and] Karafuto [Sakhalin Island], but also Hokkaido. This would destroy the foundation of Japan. We must end the war when we can deal with the United States.”[68] Furthermore, when Shigemitsu had a crucial meeting with Kido on the afternoon of August 9 at Prince Konoe’s request, which eventually led to Kido’s meeting with Hirohito that persuaded the emperor to accept the “sacred decision” scenario, Shigemitsu stressed the negative effect of further Soviet expansion on the fate of the imperial household.[69]

What motivated Hirohito was neither a pious wish to bring peace to humanity nor a sincere desire to save the people and the nation from destruction, as his imperial rescript stated and as the myth of the emperor’s “sacred decision” would have us believe. More than anything else, it was a sense of personal survival and deep responsibility to maintain the imperial house, which had lasted in unbroken lineage since the legendary Jinmu emperor. For that purpose, Hirohiro was quick to jettison the pseudo-religious concept of the kokutai, and even the emperor’s prerogatives as embodied in the Meiji Constitution. What mattered to him was the preservation of the imperial house, and to that end, he was willing to entrust his fate to the will of the Japanese people. Hirohito’s transformation from a living god (arahitogami) to a human emperor (ningen tenno), which is seen as having occurred during the American occupation, actually took place during the final “sacred decision” at the imperial conference. With astonishing swiftness, the members of the imperial house closed ranks and defended Hirohito’s decision. To attain this objective, Hirohito was prepared to part with the military and the ultranationalists, who were major obstacles.

It is difficult to document just how the Soviet factor influenced the emperor’s decision and the thinking of his close advisers. It is possible to conjecture, however, that the emperor and his advisers wished to avoid any Soviet influence in determining the fate of the imperial household and the emperor’s status. It is not far-fetched to assume that Suzuki’s statement and Shigemitsu’s thinking quoted above, which explain the need to accept the Byrnes note before the Soviet Union expanded its conquered territories, was widely shared by the ruling circles in Japan.

There was another factor in the political calculations of the Japanese ruling elite: fear of popular unrest. On August 12, Navy Minister Yonai Mitsumasa told Takagi Sokichi: “They may not be the appropriate words, but the atomic bombs and the Soviet entry into the war are in a way a godsend, since we don’t have to decide to stop the war because of the domestic situation. The reason why I have advocated the end of war is not that I was afraid of the enemy’s attack, nor was it because of the atomic bombs or the Soviet entry into the war. It was more than anything else because I was afraid of domestic conditions. Therefore, we were fortunate to [be able to] end the war without pushing the domestic situation to the fore.”[70] Yonai’s fear was widely shared by the ruling elite. Konoe’s advocacy of peace, which he had submitted to Hirohito in February 1945, was motivated by his fear of a communist revolution. Whether or not such a revolution was actually likely or even possible, the fear among the ruling elite of such popular unrest sweeping away the entire emperor system was quite real. On August 13, 14, and 15, Kido met Machimura Kingo, chief of the Metropolitan Police, to hear reports of possible political and social turmoil at home.[71]

The Psychological Factor

The complicated political calculations of the Japanese leadership were closely intermingled with crucial psychological factors. In particular, there were two different psychological elements at work. The first was the reversal of the degree of hatred attached to two enemies, as described above. The second was a profound sense of betrayal.

Soviet entry into the war had double-crossed the Japanese in two distinct senses. In the first place, the Kremlin had opted for war just when Japan was pinning its last hopes of peace on Soviet mediation. Furthermore, the invasion was a surprise attack. True, Molotov had handed a declaration of war to Sato in Moscow. Sato then asked for Molotov’s permission to transmit the declaration of war to Tokyo by ciphered telegram, but the ambassador’s dispatch never reached Tokyo. In fact, it never left Moscow, most likely having been suppressed by the telegraph office on the orders of the Soviet government. Molotov announced that the declaration of war was also to be handed by Soviet Ambassador Iakov Malik to Togo in Tokyo simultaneously. But the Japanese government learned of the Soviet invasion of Manchuria only from a news agency report at around 4:00 A.M. on August 9.[72]

Soviet tanks in Manchuria 1945

Matsumoto Shun’ichi explained Togo’s rage when he received the news of the Soviet invasion of Manchuria. Togo had gullibly believed assurances about the Soviet commitment to the neutrality pact, and he had pinned his hopes on Soviet mediation to terminate the war. Not only did this turn out to be a mistake, but the Soviet action also revealed that the Japanese government had been consistently and thoroughly deceived. Togo’s determination to end the war by accepting the Potsdam terms was thus motivated by his desire to compensate for his earlier mistake in seeking Moscow’s mediation.[73] Hirohito’s monologue also had a tinge of resentment toward the Soviet Union, which he too had mistakenly relied upon to mediate a termination to the war.[74] Togo and his colleagues were also anxious to deny the Soviet Union any advantage, since it had perpetrated such a betrayal. After the Soviet entry into the war, the USSR and matters related to the military situation in Manchuria suddenly disappeared from the discussions of Japanese policymakers. This does not mean that the Soviet factor had lost importance. In fact, their silence on the Soviet factor in these discussions was proof of both a conscious and unconscious attempt at denial. The greater their sense of betrayal, the more determined Japanese leaders became to deny the importance of Soviet entry into the war. They avoided denouncing Moscow’s perfidy, because they did not want to reveal the colossal error they themselves had committed in seeking Soviet mediation. And now that the fate of the emperor and the imperial house hung in the balance, they wished those issues to be determined by the United States rather than the Soviet Union. These conscious and unconscious manipulations of memory and historical records began simultaneously with events as they unfolded and continued subsequently in order to reconstruct these crucial events.

Interpreting the Evidence

To prove the decisiveness of the atomic bomb, Asada cites the testimonies given by Kido and Sakomizu. Kido, he says, stated: “I believe that with the atomic bomb alone we could have brought the war to an end. But the Soviet entry into the war made it that much easier.”[75] Sakomizu’s testimony to Allied interrogators stated: “I am sure we could have ended the war in a similar way if the Russian declaration of war had not taken place at all.”[76] To borrow Frank’s expression, these testimonies “should be approached with circumspection,” not because they were given years after the events, but because their veracity is questionable. Kido was prominent among those who attempted to create the myth that the emperor’s “sacred decision” had saved the Japanese people and the Japanese nation from further destruction. On different occasions, both Kido and Sakomizu told a different story.

In an interview with the Diet Library in 1967, Kido stated: “Things went smoothly. The atomic bombs served their purpose, and the Soviet entry served its purpose. They were both crucial elements [umaku iku yoso to natta]. I believe that Japan’s recovery as we see it today was possible because of the Soviet [entry into the war] and the atomic bombs.”[77] Sakomizu’s memoirs also convey a different picture from that put forward by Asada. When Sakomizu heard the news of the Soviet invasion of Manchuria from Hasegawa Saiji of the Domei News Service, he writes, he was “really surprised” and asked: “Is it really true?” He says that he felt “as if the ground on which I stood was collapsing.” While Hasegawa was double-checking the accuracy of the report, Sakomizu “felt the anger as if all the blood in the body was flowing backward.”[78] This testimony was corroborated by Hasegawa, who remembered: “When I conveyed the news [about the Soviet declaration of war] to Togo and Sakomizu, both were dumbfounded. Togo repeatedly asked me: ‘Are you sure?’ since he was expecting Moscow’s answer regarding mediation.”[79]

Many in the ruling elite considered the atomic bombs and Soviet entry into the war as god-given gifts (tenyu). Like Kido, in the statement quoted above, Yonai thought both the atomic bomb and the Soviet entry into the war were gifts from heaven.[80] and when Konoe heard the news of the Soviet invasion, he said “in order to control the Army, it may be a god-sent gift.”[81] Surveying the discussions at Supreme War Council meetings and cabinet meetings, there are some references only to the atomic bombs (such as Suzuki’s statement quoted above), others to Soviet entry into the war alone (such as Konoe’s statement), and still others to both (such as Yonai’s remarks) in advocating peace. Choosing passages that merely emphasize the effect of the atomic bombs and ignoring other passages is not sound analytical practice. It should be noted, too, that all these references were made only after the Soviet Union entered the war.

To prove that the atomic bombing on Hiroshima had a decisive effect on Hirohito’s “sacred decision,” Asada cites the emperor’s statement at the imperial conference on August 9–10. According to Asada, Hirohito allegedly said that it would be impossible to continue the war, “since the appearance of the atomic bomb.[82] Frank also singles out the emperor’s speech on August 10 as one of the most crucial pieces of evidence proving the decisiveness of the atomic bomb. According to Frank, “the Emperor also explicitly cited two military considerations: inadequate preparations to resist the invasion and the vast destructiveness of the atomic bomb and the air attacks. He did not refer to Soviet intervention.”[83] For this assertion, both Asada and Frank rely on a single source: Takeshita Masahiko’s Kimitsu sakusen nisshi.[84] The emperor’s reference to the atomic bombs appears only in Kimitsu -sakusen nisshi. Since Takeshita did not participate in the imperial conference, his account must have come from Anami, who was his brother-in-law. None of the participants recall that Hirohito referred to the atomic bombs in his speech. In fact, Togo’s memoirs and Sakomizu’s memoirs, quoted in Shusen shiroku, which Asada cites as the evidence that the emperor specifically cited the atomic bomb as the major reason for his decision, actually does not contain this reference.[85] Frank concedes that at this meeting with Japan’s most senior military officers on August 14, the emperor cited both Soviet intervention and “the enemy’s scientific power.” This was “the only contemporary instance where the Emperor saw Soviet intervention as significant,” Frank writes, adding, “and even then he coupled it with the atomic bomb.” In the imperial rescript, Frank says, “the emperor spoke explicitly on one point: the enemy’s employment of a ‘new and most cruel bomb.’”[86]

Silence, however, does not necessarily mean that the Soviet entry had little effect on Hirohito’s decision to surrender. It is true that the emperor did not refer to the Soviet entry in his imperial rescript to the general Japanese population on August 15. But Frank ignores another important document: the imperial rescript addressed to the soldiers and sailors, issued on August 17, which states:

Now that the Soviet Union has entered the war against us, to continue … under the present conditions at home and abroad would only recklessly incur even more damage to ourselves and result in endangering the very foundation of the empire’s existence. Therefore, even though enormous fighting spirit still exists in the imperial navy and army, I am going to make peace with the United States, Britain, and the Soviet Union, as well as with Chungking, in order to maintain our glorious kokutai.[87]

To the soldiers and sailors, especially die-hard officers who might still wish to continue fighting, the emperor did not mention the atomic bomb. Rather, it was Soviet participation in the war that provided a more powerful justification to persuade the troops to lay down their arms.[88]

Frank is absolutely right in pointing out that “[t]he end of hostilities required both a decision by a legitimate authority that Japan must yield to Allied terms and compliance by Japanese armed forces with that decision,” and that such legitimate authority was the emperor. He is also right about the inability of the Suzuki government to accept unconditional surrender without the emperor’s intervention.[89] It is true that the emperor’s strong desire to terminate the war played a decisive role in his “sacred decision.” Nevertheless, it seems erroneous to attribute the emperor’s motivation for this decision to what he said in the imperial rescripts. Now united behind the “sacred decision,” the cabinet set out to persuade the Japanese people, both civilians and men in uniform, to accept surrender. The cabinet therefore made a few revisions to Sakomizu’s draft of the imperial rescript.

Two documents issued by the cabinet need to be examined. The first is a cabinet statement released after the imperial rescript was broadcast, which refers to both the use of the atomic bomb, which changed the nature of war, and the Soviet entry as two important reasons for ending the war.[90] The second is the prime minister’s radio announcement of August 15, in which he stated that Soviet entry into the war had prompted the cabinet to make the final decision to end the war, and that the atomic bomb, which “it was evident the enemy will continue to use,” would destroy both the military power of the empire “and the foundation of the existence of the nation, endangering the basis of our kokutai.”[91] Both documents cite the atomic bomb and the Soviet entry into the war as the two important reasons that had prompted the government to seek the termination of the war, thus invalidating Frank’s claim that the atomic bomb had a more decisive effect on the emperor’s decision to end the war.

5. Counterfactual Hypotheses

A series of counterfactual hypotheses can help clarify the question of which factor, the atomic bombs or Soviet entry into the war, had the more decisive effect on Japan’s decision to surrender. We might ask, in particular, whether Japan would have surrendered before November 1, the scheduled date for the start of Operation Olympic, the U.S. invasion of Kyushu, given (a) neither the atomic bombings of Hiroshima and Nagasaki nor Soviet entry into the war; (b) Soviet entry alone, without the atomic bombings; or (c) the atomic bombings alone, without Soviet entry.[92]

Let us examine the first proposition. The Summary Report (Pacific War) of the United States Strategic Bombing Survey, published in 1946 concluded that Japan would have surrendered before November 1 without the atomic bombs and without the Soviet entry into the war. This conclusion has become the foundation on which the revisionist historians constructed their argument that the atomic bombs were not necessary for Japan’s surrender.[93] Since Barton Bernstein has persuasively demonstrated in his devastating critique of the U.S. Strategic Bombing Survey that its conclusion is not supported by its own evidence, I need not dwell on this supposition.[94] It suffices to state that, contrary to its conclusion, the evidence the Strategic Bombing Survey relied on overwhelmingly demonstrates the decisive effect of the atomic bombs and Soviet entry on Japan’s decision. As Bernstein asserts: “[A]nalysts can no longer trust the Survey’s statement of counterfactual probabilities about when the Pacific War would have ended without the A-bomb or Soviet entry. On such matters, the Survey is an unreliable guide.” I concur with his conclusion: “[I]t is time for all to stop relying upon the United States Strategic Bombing Survey’s pre-November 1945, surrender-counterfactual for authority.”[95]

For the second counterfactual hypothesis, that is, surrender with the Soviet entry alone, Asada contends: “[T]here was a possibility that Japan would not have surrendered before November 1.”[96] By making this assertion, Asada ignores an important conclusion made by Bernstein. Bernstein states: “In view of the great impact of Soviet entry, however, in a situation of heavy conventional bombing and a strangling blockade, it does seem quite probable—indeed, far more likely than not—that Japan would have surrendered before November without the use of the A-bomb but after Soviet intervention in the war. In that sense … there may have been a serious ‘missed opportunity’ in 1945 to avoid the costly invasion of Kyushu without dropping the atomic bomb by awaiting Soviet entry.”[97] However, since it was inessential at that point in his essay, Bernstein does not fully develop his argument.

As I have argued above, Japan relied on Soviet neutrality both militarily and diplomatically. Diplomatically, Japan pinned its last hope on Moscow’s mediation for the termination of the war. Only by Soviet entry into the war was Japan forced to make a decision on the Potsdam terms. Militarily as well, Japan’s Ketsu Go strategy was predicated on Soviet neutrality. That was why the General Staff’s Bureau of Military Affairs constantly overruled the Fifth Department’s alarming warnings that a Soviet invasion might be imminent. Manchuria was not written off, as Frank asserts; rather, the military was confident that it could keep the USSR neutral, at least for a while. When the Soviet invasion of Manchuria occurred, the military was taken completely by surprise. Even Asada admits, “[T]he Soviet entry spelled the strategic bankruptcy of Japan.”[98] Despite the repeated bravado calling for the continuation of the war, it pulled the rug right out from underneath the Japanese military, puncturing a gaping hole in their strategic plan. Their insistence on the continuation of the war lost its rationale.
Without Japan’s surrender, it is reasonable to assume that the USSR would have completed the occupation of Manchuria, southern Sakhalin, the entire Kurils, and possibly even the Korean peninsula, by the beginning of September. Inevitably, Soviet invasion of Hokkaido would have emerged as a pressing issue to be settled between the United States and the Soviet Union. The United States might have resisted a Soviet operation against Hokkaido, but given Soviet military strength, and given the enormous casualty figures the American high command had estimated for Olympic, the United States might have agreed to a division of Hokkaido as Stalin envisaged. Even if it succeeded in resisting Stalin’s pressure, Soviet military conquests in the rest of the Far East might have led the United States to concede some degree of Soviet participation in Japan’s postwar occupation. Whatever the United States might or might not have done regarding Soviet operations in Hokkaido or the postwar occupation of Japan, Japanese leaders were well aware of the danger of allowing continued Soviet expansion beyond Manchuria, Korea, and Sakhalin. That was one of the very powerful reasons why the Japanese ruling elite coalesced at the last moment to surrender under the Potsdam terms, why the military’s insistence on continuing the war collapsed, and why the military relatively easily accepted surrender. Japan’s decision to surrender was above all a political decision, not a military one. It was more likely, therefore, that even without the atomic bombs, the war would have ended shortly after the Soviet entry into the war, almost certainly before November 1.

Asada does not ask whether Japan would have surrendered with the atomic bombing of Hiroshima and Nagasaki alone, without the Soviet entry into the war. It is most likely that the two bombs alone would not have prompted Japan to surrender, as long as it still had the hope of attaining a mediated peace through Moscow. As I have shown, the Hiroshima bomb did not significantly change Japan’s policy except for injecting a sense of urgency in seeking an end to the fighting. Without the Soviet entry into the war, I do not see how the Nagasaki bomb would have changed the situation. Japan would most likely still have waited for Moscow’s answer to the Konoe mission even after the Nagasaki bomb. The most likely scenario would have been that while waiting for an answer from Moscow, Japan would have been surprised by the Soviet invasion of Manchuria sometime in the middle of August and would have sued for peace on the Potsdam terms. We would then have debated endlessly about whether the two atomic bombs preceding the Soviet invasion or the Soviet entry had the greater influence on Japan’s decision to surrender. In this case, too, however, Soviet entry would clearly have had a more decisive effect for the reasons stated above.

Without Soviet participation in the war in the middle of August, the United States would have faced the question of whether it should use a third bomb sometime after August 19, and then a fourth bomb early in September, most likely on Kokura and Niigata. It is hard to say how many atomic bombs it would have taken to compel the Japanese ruling elite to abandon their approach to Moscow. It is possible to argue, although it is impossible to prove, that the Japanese military would have still argued for the continuation of the war even after the dropping of a third bomb, and even after a fourth bomb. Could Japan have withstood the attacks of all seven atomic bombs scheduled to be produced before November 1?[99] Would the United States have had the resolve to use seven atomic bombs in succession? What would have been the effect of these bombs on Japanese public opinion? Would the continuing use of the bombs have solidified the resolve of the Japanese to fight or eroded it? Would it have hopelessly alienated the Japanese from the United States, to the point where it would have been difficult to impose the American occupation on Japan? Would it have encouraged the Japanese to welcome a Soviet occupation instead? These are the questions I cannot answer with certainty.
But what I can state is that the two atomic bombs on Hiroshima and Nagasaki were not likely to be decisive in inducing Japan to surrender. Without the Soviet entry into the war between the two bombs, Japan would most likely have continued the war.

There still remains one important hypothesis to consider. What if Truman had asked Stalin to join the Potsdam Proclamation and retained the promise to the Japanese to allow the preservation of a constitutional monarchy, as Stimson’s original draft of the proclamation had suggested? This scenario would not have assured Japan’s immediate acceptance of the Potsdam terms, since it would surely have encountered the army’s insistence on three other conditions. It is not even certain that the army would have accepted a constitutional monarchy, which was certainly not consistent with its understanding of the kokutai. Nevertheless, it would have strengthened the resolve of the peace party to seek the termination of the war, and would have made it easier for it to accept the terms, knowing that a monarchical system would be preserved and that Moscow might be harsher and demand the elimination of the emperor system.

But inviting Stalin to join the joint ultimatum and compromising on the unconditional surrender terms were not an option that Truman and Secretary of State James Byrnes would have considered. Although Secretary of War Henry Stimson, Admiral William Leahy, General George Marshall, Assistant Secretary of War John McCloy, Secretary of the Navy James Forrestal, and Acting Secretary of State Joseph Grew would all have preferred this, to Truman and Byrnes, it was anathema. Ironically, it was the atomic bomb that made it possible for Truman to be able to issue the Potsdam Proclamation demanding unconditional surrender without Stalin’s signature. The atomic bomb also changed the very nature of the Potsdam Proclamation. Instead of being a final warning before Olympic, as originally intended, it became the justification for the use of the atomic bomb. In this sense, the revisionist historians’ claim that the atomic bomb delayed rather than hastened Japan’s surrender merits serious consideration.

6. Conclusions

The argument presented by Asada and Frank that the atomic bombs rather than Soviet entry into the war had a more decisive effect on Japan’s decision to surrender cannot be supported. The Hiroshima bomb, although it heightened the sense of urgency to seek the termination of the war, did not prompt the Japanese government to take any immediate action that repudiated the previous policy of seeking Moscow’s mediation. Contrary to the contention advanced by Asada and Frank, there is no evidence to show that the Hiroshima bomb led either Togo or the emperor to accept the Potsdam terms. On the contrary, Togo’s urgent telegram to Sato on August 7 indicates that, despite the Hiroshima bomb, they continued to stay the previous course. The effect of the Nagasaki bomb was negligible. It did not change the political alignment one way or the other. Even Anami’s fantastic suggestion that the United States had more than 100 atomic bombs and planned to bomb Tokyo next did not change the opinions of either the peace party or the war party at all.

Rather, what decisively changed the views of the Japanese ruling elite was the Soviet entry into the war. It catapulted the Japanese government into taking immediate action. For the first time, it forced the government squarely to confront the issue of whether it should accept the Potsdam terms. In the tortuous discussions from August 9 through August 14, the peace party, motivated by a profound sense of betrayal, fear of Soviet influence on occupation policy, and above all by a desperate desire to preserve the imperial house, finally staged a conspiracy to impose the “emperor’s sacred decision” and accept the Potsdam terms, believing that under the circumstances surrendering to the United States would best assure the preservation of the imperial house and save the emperor.

This is, of course, not to deny completely the effect of the atomic bomb on Japan’s policymakers. It certainly injected a sense of urgency in finding an acceptable end to the war. Kido stated that while the peace party and the war party had previously been equally balanced in the scale, the atomic bomb helped to tip the balance in favor of the peace party.[100] It would be more accurate to say that the Soviet entry into the war, adding to that tipped scale, then completely toppled the scale itself.

Tsuyoshi Hasegawa is professor of modern Russian and Soviet history, University of California, Santa Barbara and the author of Racing the Enemy: Stalin, Truman, and the Surrender of Japan.
This is a slightly revised version of an essay published in From The End of the Pacific War, Reappraisals, edited by Tsuyoshi Hasegawa , (c) 2007 by the Board of Trustees of the Leland Stanford Jr. University. All rights reserved. No further reproduction or distribution is allowed without the prior written permission of the publisher, Posted at Japan Focus on August 17, 2007.


[1] On the American debate about the use of the atomic bombs, see Barton J. Bernstein, “The Struggle over History: Defining the Hiroshima Narrative, in Judgment at the Smithsonian, ed. Philip Nobile, 127–256 (New York: Marlowe, 1995).
[2] Sadao Asada, “The Shock of the Atomic Bomb and Japan’s Decision to Surrender—A Reconsideration,” Pacific Historical Review 67, no. 4 (1998): 481.
[3] See, e.g., the interesting exchange between Alperovitz/Messer and Bernstein in International Security 16 (1991–92). Neither Alperovitz/Messer nor Bernstein confronts the issue of the Soviet factor in inducing Japan to surrender. Gar Alperovitz in his The Decision to Use the Atomic Bomb and the Architecture of an American Myth (New York: Knopf, 1995) devotes more than 600 pages to the U.S. motivation for using the atomic bombs, but does not directly address the question of whether the atomic bombings or the Soviet entry had the more decisive influence on Japan’s decision to surrender.
[4] Asada, “Shock,” 479–83; its Japanese version, Asada Sadao, “Genbaku toka no shogeki to kohuku no kettei,” in Hosoya Chihiro et al., Taihei senso no shuketsu (Tokyo: Kashiwa shobo, 1997), 195–222; and Richard B. Frank, Downfall: The End of the Imperial Japanese Empire (New York: Random House, 1999), 271.
[5] Asada, “Shock,” 486.
[6] Frank, Downfall, 271. Frank’s source is Asada’s article. Frank also cites Robert J. C. Butow, Japan’s Decision to Surrender (Stanford: Stanford University Press, 1959), 152–53, but Butow has nothing to say about the August 7 cabinet meeting. Frank explains that Asada’s source is Togo Shigenori, Jidai no ichimen (Tokyo: Kaizosha, 1952; reprint, Hara shobo, 1989), but Togo’s memoirs are silent about the Potsdam Proclamation.
[7] Togo, Jidai no ichimen, 355. In his notes written in September 1945, Togo referred to the cabinet meeting on August 7 without saying that he had proposed the acceptance of the Potsdam Proclamation. See “Togo gaiso kijutsu hikki ‘Shusen ni saishite’ September 1945,” in Gaimusho, ed., Shusen shiroku (Tokyo: Hokuyosha, 1977), 4: 60.
[8] Kurihara Ken and Hatano Sumio, eds., Shusen kosaku no kiroku (Tokyo: Kodansha, 1986), 2: 355–56.
[9] Sakomizu Hisatsune, Kikanju ka no shusho kantei (Tokyo: Kobunsha, 1964), 243-44. Sakomizu published another memoir in 1973, Dainihon teikoku saigo no yonkagetsu (Tokyo: Orientosha, 1973), but he makes no reference to the August 7 cabinet meeting in the later book.
[10] Kido Nikki Kenkyukai, ed., Kido Koichi nikki (Tokyo: Tokyo daigaku shuppankai, 1966), 2: 1222.
[11] Kido Koichi nikki: Tokyo saibanki (Tokyo: Tokyo Daigaku shuppankai, 1980), 421.
[12] Asada, “Shock,” 487.
[13] Frank, Downfall, 272.
[14] Tanaka Nobunao, Dokyumento showa tenno 5, Haisen Vol. 2 (Tokyo: Ryokufu Shuppan, 1988), 2: 460–61.
[15] Quoted in Asada, “Shock,” 488.
[16] Ibid.
[17] Frank, Downfall, 272.
[18] Togo’s statement comes from his memoirs, Jidai no ichimen, 355–56. Asada does not include the words in brackets in the Japanese version. See Asada, “Genbaku toka,” 199.
[19] During an interview with Oi Atsushi for the military history project of Military Intelligence Section of the General Staff of the Supreme Commander for the Allied Powers (SCAP), Togo said that he suggested to the emperor on August 8 that Japan should accept the Potsdam terms. Continuing the question, Oi tried to establish that Togo and the emperor had already decided to terminate the war on the terms stipulated in the Potsdam Proclamation before the Soviet entry into the war. Togo equivocated, saying that Soviet mediation would not be limited only to the clarification of the Potsdam terms. He was not sure whether the Kremlin would convey Japan’s wishes to the Allied powers or would take the trouble to make an arrangement for Japan to hold direct negotiations with the United States and Britain. To this, Oi interjected by saying that whether they went through Moscow or by a direct route, the meaning was that the war would be terminated on the basis of the Potsdam Proclamation. Togo agreed, but without conviction. “Togo Shigenori chinjutsuroku,” in Kurihara and Hatano, eds., Shusen kosaku no kiroku, 2: 357–58.
[20] Sakomizu Hisatsune, Dai Nihonteikoku saigo no 4-kagetsu (Tokyo: Oriento shobo, 1973), 185.
[21] Asada, “Shock,” 489.
[22] Sakomizu, Dai Nihon teikoku, 185, 187.
[23] Sakomikzu, Kikanju ka no shusho kantei, 245–46.
[24] Hasegawa Saiji, “Hokai no zenya,” Fujin koron, August 1947, in Gaimusho, ed., Shusen shiroku, 5: 84.
[25] Asada and Frank also cite Suzuki’s statement made in December 1945, which will be discussed later.
[26] Suzuki Hajime, ed., Suzuki Kantaro jiden (Tokyo: Jijitsushinsha, 1969), 294–95.
[27] Sakomizu’s 1964 memoirs also take this view. Sakomizu, Kikanju ka no shusho kantei, 255.
[28] Togo to Sato, telegram no. 993, 15: 40 Tokyo, Aug. 7, 1945, in Gaimusho, ed., Shusen shiroku, 4: 77.
[29] This was also confirmed by Sakomizu, who allegedly stated that Togo had made a statement at the cabinet meeting on August 7 in support of accepting the Potsdam Proclamation. Sakomizu, Kikanju ka no shusho kantei, 244–45.
[30] Information obtained by Harano Sumio.
[31] Asada, “Shock,” 491–92. This term does not appear in the Japanese version. “Asada, “Genbaku toka,” 201.
[32] Boeicho Boeikenshujo Senshishitsu, Senshi sosho: Daihonei rikugunbu, vol. 10: Showa 20 nen 8 gatsu made (Tokyo: Asagumo shinbunsha, 1975), 443.
[33] Asada, “Shock,” 504.
[34] Frank, Downfall, 348.
[35] Boeicho Boeikenshujo Senshishitsu, Kantogun,Vol. 2, Kantokuen, Shusenji no taiso sen (Tokyo: Asagumo shinbunsha, 1974), 326.
[36] Ibid..
[37] Ibid., 328.
[38] Ibid., 330.
[39] Ibid., 332; Tanemura Suetaka, Daihonei kimitsu nisshi (Tokyo: Fuyo shobo, 1995), 295.
[40] “Soren no tainichi saigo tsucho ni taishite torubeki sochi no kenkyu,” in Nishihara Masao, Shusen no keii, Vol. 1, 104-08; Kurihara and Hatano, eds., Shusen kosaku no kiroku, 2: 363–64.
[41] Boeicho Boeikenshujo Senshishitsu, Kantogun, Vol. 2, 318.
[42] Ibid., 318.
[43] Quoted in Boeicho Boeikenshujo Senshishitsu, Senshi sosho: Daihonei rikugunbu, 10: 427.
[44] Boeicho Boeikenshujo Senshishitsu, Kantogun -, Vol. 2, 330.
[45] Asada, “Shock,” 504.
[46] Kawabe Torashiro, “Jicho nisshi,” vol. 2, quoted in Boeicho Boeikenshujo Senshishitsu, Senshi sosho: Daihonei rikugunbu, 10: 430; also Kurihara and Hatano, eds., Shusen kosaku no kiroku, 2: 364. The handwritten original is Kawabe Torashiro Sanbojicho nisshi, Showa 20. 7.26–20.9.2, in Boeikenkyujo senshishitsu, chuo, senso shido juyo kokusaku bunsho, 1206. Although Daihonei rikugunbu 10 occasionally alters the original when it quotes from Kawabe’s diary, this part is accurately quoted. A slightly different version is given in Kawabe Torashiro, “Sanbo jicho no nisshi,” in Kawabe Torashiro Kaisoroku (Tokyo: Manichi shinbunsha, 1979), 253.
[47] Quoted in Boeicho Boeikenshujo Senshishitsu, Senshi sosho: Daihonei rikugunbu, 10: 420; Kawabe, “Jicho nisshi,” 252.
[48] Jicho nisshi, quoted in Boeicho Boeikenshujo Senshishitsu, Senshi sosho: Daihonei rikugunbu, 10: 440–41. This part is not included in Kawabe, “Jicho nissi,” in Kawabe Kaisoroku, 254.
[49] Jicho nisshi, quoted in Boeicho Boeikenshujo Senshishitsu, Senshi sosho: Daihonei rikugunbu, 10: 452, “Jicho nisshi” in Kawabe Kaisoroku is slightly different.
[50] # 52608, Kawabe Torashiro, Nov. 21, 1949, 5–6, Historical Manuscript File, Center for Military History [hereafter CMH]. I thank Richard Frank for allowing me to use his collection from the Center for Military History.
[51] Frank, Downfall, 346–67.
[52] Arisue kikanho, no. 333, Nov. 16, 1945, Rikugunsho, “Beikoku shireibu no ‘Teikokusakusen oyobi shido kankei shitsumon’ ni taisuru kaito, Bunko Yu, 395, Beoei Kenkyujo, Senshishitsu.
[53] # 59617, Maj. Gen. Amano Masakazu, Historical Manuscript File; also see Amano Masakazu Chinjutsusho, GHQ Senshika, vol. 6, Chuo Shusen shori 228, Boei Kenkyujo Senshishitsu. The English translation of the Historical Manuscript File is modified in view of the original Japanese testimony in the Boei kenkyujo.
[54] # 54479, Ikeda Sumihisa, Historical Manuscript File, 4–5; also see Ikeda Sumihisa Chinjutsusho, GHQ Senshika, vol. 1, Chuo Shusenshori 227, Boei Kenkyujo, Senshishitsu.
[55] Hayashi Saburo Chinjutsusho (Dec. 23, 1949), vol. 6, GHQ Senshika, Chuo Shusenshori 228, Boei Kenkyujo, Senshishitsu.
[56] # 61340, Toyoda Soemu (Aug. 29, 1949), 7–8, CMH.
[57] # 531, Suzuki Kantaro (Dec. 26, 1945), CMH.
[58] Frank, Downfall, 347.
[59] Frank’s argument is questionable in his methodology here. If he discounts Kawabe’s and Toyoda’s testimonies as having been given years after the events in question, why should Suzuki’s testimony, which was given several months after the end of the war, be deemed more reliable? Frank’s method of looking critically at testimonies made after the events is admirable, but he is inconsistent in this approach.
[60] “Gikai toben shiryo,’ Kokubo taiko kankei juyoimanaka shorui tsuzuki, Rikugunsho Gunjika, Rikugun Chusa Shigero shokan, Chuo, Sensoshido sonota 78, Boeikenkyujo Senshishitsu.
[61] Ibid.
[62] Kantogun,Vol. 2, 280–81.
[63] Ibid., 368–70.
[64] Boeicho Boeikenshujo Senshishitsu, Senshi sosho: Hokuto homen rikugun sakusen, Vol. 2: Chishima, Karafuto, Hokkaido no boei (Tokyo: Asagumo shinbunsha, 1971), 337.
[65] Ibid., 342–45.
[66] Frank, Downfall, 323.
[67] For this, see Tsuyoshi Hasegawa, Racing the Enemy: Stalin, Truman, and the Surrender of Japan (Cambridge, Mass.: Belknap Press of Harvard University Press, 2005), chaps. 5 and 6.
[68] Hando Toshikazu, Nihon no ichiban nagai hi, ed. Oya Soichi (Tokyo: Bungei shunjusha, 1973), 36. Hando does not cite his source, but this popular book, though lacking citations, seems to be based on reliable sources.
[69] Shigemitsu Mamoru, Showa no doran (Tokyo: Chukoronsha, 1952), 2: 286.
[70] Yonai Mitsumasa, “Takagi oboegaki,” quoted in Kurihara and Hatano, eds., Shusen kosaku no kiroku, 2: 379.
[71] Kido Nikki Kenkyukai, ed., Kido Koichi nikki, 2: 1225–27.
[72] Ambassador Sato, who was usually very astute, made a grave error here in assuming that Molotov’s declaration of war effective midnight August 9 meant midnight Moscow time. Soviet tanks rolled into Manchuria at midnight Transbaikal time, 6 P.M. Moscow time, less than an hour after Molotov handed Sato the declaration of war, magnifying the sense of betrayal felt by the Japanese. See Hasegawa, Racing the Enemy, chap. 5.
[73] Matsumoto Shun’ichi, “Shusen oboegaki,” in Gaimusho, ed., Shusen shiroku, 4: 158–59.
[74] Showa Tenno dokuhakuroku (Tokyo: Bungei shunju, 1991), 120–21.
[75] Asada, “Shock,” 505, citing Kido nikki: Tokyo saibanki, 444. This does not appear in the Japanese original, Asada, “Genbaku toka,” 207–8.
[76] Sakomizu, May 3, 1949, “Interrogations,” quoted in Asada, “Shock,” 505.
[77] Quoted in Wada Haruki, “Nisso senso,” in Hara Teruyuki and Togawa Tsuguo, eds., Koza Surabu no sekai, vol. 8: Surabu to nihon (Tokyo: Kobundo, 1995), 119.
[78] Sakomizu, Kikanju ka no shusho kantei, 246.
[79] Hasegawa Saiji, “Hokai no zenya,” Fujin koron, August 1947, quoted in Shusen shiroku,. 4: 84.
[80] Takagi Sokichi, Takagi kaigun shosho oboegaki (Tokyo: Mainichi shinbunsha, 1979).
[81] Hosokawa Morisada, Hosokawa Nikki (1953; reprint, Tokyo: Chuokoronsha, 1979), 2: 415.
[82] Asada, “Shock,” 495.
[83] Frank, Downfall, 345, based on Boeicho Boeikenshujo Senshishitsu, Senshi sosho: Daihonei rikugunbu, 10: 449. which comes from Daihon’ei Rikugunbu Senso Shidohan, Kimitsu senso nisshi, 2: 756. Frank cites the emperor’s statement as recreated by Butow, but Butow’s record says nothing about the emperor’s reference to the atomic bomb. But Frank inserts in brackets “[At about this point, he also made specific reference to the greatly increased destructiveness of the atomic bomb],” supposedly from “the official Japanese military history series.” Frank, Downfall, 295–96. Boeicho Boeikenshujo Senshishitsu, Daihonei rikugunbu, vol. 10, on which Frank relies, takes this part from Takeshita’s Kimitsu senso nisshi.
[84] Asada’s source is Sanbo Honbu, ed., Haisen no kiroku, 362, and Frank’s source is Boeicho Boeikenshujo Senshishitsu, Daihonei rikugunbu , 10: 449, but the original source of both is Takeshita’s Kimitsu sakusen nisshi.
[85] Gaimusho, ed., Shusen shiroku, 4: 139, 142. In addition to the excerpts from Togo and Sakomizu, Shusen shiroku also contains excerpts from Toyoda and Hoshina Zenshiro, who attended the imperial conference, and Kido and Shimomura, who did not. None of them mention anything about the emperor’s reference to the atomic bomb.
[86] Frank, Downfall, 345–46.
[87] “Rikukaigunjin ni taisuru chokugo,” in Hattori Takushiro, Daitoa senso zenshi (Harashobo, 1965) 948, translation based on Herbert P. Bix, Hirohito and the Making of Modern Japan (New York: HarperCollins, 2000), 530, with a slight modification.
[88] Sakomizu was the author of the imperial rescript on the termination of the war. Sakomizu had been drafting the rescript since the first imperial conference on August 9–10. After the second imperial conference was over, he returned to the prime minister’s residence to revise the draft in view of the emperor’s statement at the imperial conference. Since he had to revise the draft to be presented to the cabinet under pressure of time, he asked his subordinate Kihara Michio to prepare the draft of the imperial rescript for the soldiers and sailors. Hando, Nihon no ichiban nagai hi, 45. Presumably, Sakomizu gave Kihara the basic ideas along which the rescript should be written. But it is not clear why only the atomic bomb, not Soviet entry into the war, was mentioned in the imperial rescript for the termination of the war, why Soviet entry into the war, but not the atomic bomb, was mentioned in the later rescript, or whether Kihara consulted any military leaders. It seems likely, however, that the draft was completed by August 15.
[89] Frank, Downfall, 344.
[90] “Naikaku kokuyu,” in Matsutani Makoto, Shusen ni kansuru shiryo, Matsutani shiryo, Shusenji shiryo, Chuo, Shusen shori 236, Boei Kenkyujo, Senshishitsu.
[91] “Taisho o haishite,” in Matsutani Makoto, Shusen ni kansuru shiryo, Matsutani shiryo, Shusenji shiryo, Chuo, Shusen shori 236, Boei Kenkyujo, Senshishitsu.
[92] This part of the argument is taken partially from Hasegawa, Racing the Enemy, 294–98.
[93] U.S. Strategic Bombing Survey, Summary Report (Pacific War) (Washington, D.C.: Government Printing Office, 1946), 26. See Alperovitz, Decision to Use the Atomic Bomb, 4, 321, 368–69, 464, 465.
[94] Barton J. Bernstein, “Compelling Japan’s Surrender Without the A-bomb, Soviet Entry, or Invasion: Reconsidering the US Bombing Survey’s Early-Surrender Conclusion,” Journal of Strategic Studies 18, no. 2 (June 1995): 101–48.
[95] Ibid., 105, 127. Asada also agrees with Bernstein’s conclusion on the assessment of the U.S. Strategic Bombing Survey. Asada, “Shock,” 511.
[96] Asada, “Shock,” 510–11.
[97] Bernstein, “Compelling Japan’s Surrender,” 129. Asada cites Bernstein’s article, but only for the criticism of the U.S. Strategic Bombing Survey. He doe not refer to Bernstein’s important assertion that Japan would likely have surrendered before November after the Soviet intervention, without the use of the A-bomb, which directly contradicts Asada’s assertion.
[98] Asada, “Shock,” 504.
[99] Maj. Gen. John E. Hull and Col. L. E. Seeman, telephone conversation, Aug. 13, 1945, 13:25, verifax 2691, George C. Marshall Papers, George C. Marshall Library.
[100] Kido Koichi Kenkyukai, ed., Kido Koichi nikki: Tokyo saibanki, 444.

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Authors: For all articles by the author, click on author's name.   Tsuyoshi Hasegawa