What Did Truman Actually Decide? — August 1945, Reread After the Files Opened

In the summer of 1945, World War II was in its final phase. In Europe, Germany had surrendered that May, but in the Pacific, the war between the Allies led by the United States and Japan was ongoing. While fighting Germany, the Soviet Union had maintained a neutrality pact with Japan and was not yet at war with it. When President Franklin Roosevelt passed away in April 1945, Vice President Harry Truman became the 33rd President of the United States. The United States had been developing atomic bombs through a secret project called the Manhattan Project and was also preparing an operation to land on the Japanese mainland. This article covers the decisions leading up to the United States dropping atomic bombs on Hiroshima and Nagasaki, Japan, that August. These two cities remain the only ones where nuclear weapons have been used in actual warfare.

The conventional wisdom consists of two sentences. Truman decided to use the atomic bomb to save hundreds of thousands of lives that would be lost in a mainland invasion. The two bombs on Hiroshima and Nagasaki forced Japan to surrender. In a December 1945 poll, fewer than 5 percent of Americans answered that the bomb should not have been used. This figure was transcribed from a book review discussing recent work by historian Alex Wellerstein, The Most Terrible Responsibility (DOI: 10.1162/jcws.r.1314).

Over the subsequent 80 years, documents have opened up piece by piece. Magazine contributions from 1946–47 came first. Postwar memoirs and Truman's diary, which was only unearthed in 1980, followed. After the Cold War ended, Soviet-side documents opened further, and on the Japanese side, materials not included in the original collections entered the debate. Every time a document opened, one sentence of the conventional wisdom shook. This article follows that sequence. The names of two historians will appear frequently hereafter. They are American historian Barton Bernstein, who has re-examined the postwar solidified explanations using documents from 1945, and historian Tsuyoshi Hasegawa, who argues that Soviet entry into the war was more decisive to Japan's surrender than the atomic bomb. What Truman actually decided remains a question upon which historians are still divided. So is what caused Japan to surrender. This article does not answer those questions, but shows which documents support which interpretations.

Ten Days in Potsdam — Twenty Sheets of Cheap Paper

July 16, 1945, in the suburbs of Berlin, Potsdam. At a gathering where the leaders of the United States, Britain, and the Soviet Union met to discuss post-war settlements, Truman met British Prime Minister Winston Churchill for the first time. Two days later, on the 18th, he met Soviet Supreme Leader Joseph Stalin. The sole record of both meetings is a diary hurriedly scrawled by Truman. He wrote it intermittently from July 16 to 30. It was close to twenty sheets of cheap paper (DOI: 10.1111/j.1467-7709.1980.tb00351.x).

On that same July 16, the first atomic bomb test succeeded in Alamogordo, New Mexico. Japan also had an atomic bomb development program. Five days later, on the 21st, Japanese atomic scientists concluded once again that such a weapon was impossible (DOI: 10.1163/187656103793645261). Truman in Potsdam and scientists in Tokyo held completely opposite pieces of information in the same week.

The diary emerged from a pile of papers belonging to press secretary Charles Ross at the Truman Library. It had neither been published nor cited before it appeared in the 1980 issue of the American diplomatic history journal Diplomatic History. In the diary, Truman refers to "the President of the United States" in the third person. He broods over the atomic bomb and the ruins of Berlin. He wrote, "I want any kind of peace, but I am afraid that machinery is several centuries ahead of morals." The final memo is "A sick situation at best" (DOI: 10.1111/j.1467-7709.1980.tb00351.x). These are about the extent of Truman's inner thoughts from 1945 that this article confirmed through the abstract. What he believed can only be stated to the extent written in the diary.

On July 26, the Potsdam Declaration was issued. The Potsdam Declaration is a joint declaration issued on July 26, 1945, in which the United States, Great Britain, and China demanded unconditional surrender from Japan. Unconditional surrender is a surrender that attaches not a single condition and leaves oneself to the disposal of the opponent. This phrase was first uttered by President Roosevelt at a US-UK summit held in Casablanca, North Africa, in January 1943. One rhetoric study suggests that by 1945 this slogan had become a catchphrase that cornered policymakers (DOI: 10.1080/00335638309383664). The declaration demanded "the unconditional surrender of all Japanese armed forces." The alternative was "prompt and utter destruction" (DOI: 10.4324/9781315664637-9). There was also the sentence, "We will not deviate from those conditions. There is no alternative. We shall brook no delay" (DOI: 10.4324/9781315052038-6). Tokyo did not answer. One research book notes that Japan might have mistaken this for wartime propaganda (DOI: 10.4324/9781315664637-9). Hasegawa views that Stalin was "completely caught off guard" by Truman in this declaration (DOI: 10.4000/monderusse.7533).

Four Paths on the Desk — Invasion, Conventional Bombing, Condition Relaxation, and the Soviet Union

In Truman's postwar memoirs, there is a figure of "500,000 American lives." The claim is that an invasion would have required that many. Bernstein set out to find the source of that figure in 1945 documents. There is no evidence in the 1945 records that Truman was advised of "500,000." His conclusion is that the opposing evidence is considerable. He also wrote that, given the scale of forces committed for operations in 1945-46, 500,000 U.S. combat deaths was implausible (DOI: 10.1080/01402399908437744). Bernstein was already making the same point in 1986. Military planners during and immediately after the war used much lower figures (DOI: 10.1080/00963402.1986.11459388). Bernstein analyzes that this figure was constructed for the memoirs over several numbers that Truman handed directly to his ghostwriters. Truman cited several different numbers both while in office and after leaving office (DOI: 10.1080/01402399908437744). There were opposing arguments as well. A 1995 naval magazine article argued that casualties from an invasion in November 1945 would have been very heavy. Bernstein criticized that article for misreading historical materials and omitting key documents (DOI: 10.1111/0149-0508.00119). This article does not pick either figure. "500,000" is a number from the postwar memoirs, and the 1945 planners' numbers were lower than that. That is as far as the documents go.

Where did the binary choice of "the atomic bomb or an invasion" come from? The orthodox interpretation is the explanation that the atomic bomb was necessary to end the war and avoid an invasion. It is also the initial explanation put forward by the participants involved in the decision. According to a literature compilation published in 2013 by historian J. Samuel Walker, this interpretation painted a picture where Truman was placed between two choices. Japan's refusal to surrender is what placed him there (DOI: 10.1017/cbo9781139021760.006). Other paths had also been raised in the documents.

One path is changing the conditions. Revisionism is the interpretation that Japan would have surrendered even without the atomic bombs, and that the motives for using them went beyond ending the war. Revisionist historians have repeatedly argued that if the Japanese state system with the Emperor at its apex—namely, the imperial system—had been guaranteed, Japan would have laid down its arms immediately (DOI: 10.1163/24683302-20190005). A 2019 paper views it the other way around. It argues that U.S. authorities had justifiable grounds not to expect such concessions to end the war quickly (DOI: 10.1163/24683302-20190005). Separate from the Emperor issue, the timing and method of breaking the power of the Japanese army to extract a surrender still remained. This path remains a point of contention between the two interpretations today.

Another path is the Soviet Union. At the Allied conferences in Moscow and Tehran in the autumn of 1943, Stalin promised to fight Japan after Germany surrendered. At the Yalta Conference, where the three U.S., British, and Soviet leaders discussed the postwar order, he was promised the Kuril Islands, the islands north of Hokkaido, in exchange (DOI: 10.4000/monderusse.7533; DOI: 10.4324/9781315606521-11). According to Hasegawa's book Racing the Enemy, Stalin secretly prepared to enter the war while pretending to offer mediation to Japan. Tokyo's peace faction was struggling to block the war faction, which was shouting for a decisive battle (DOI: 10.1515/9781644699812). The same book views the U.S. side as weighing between ending the war and checking the Soviet advance into the Pacific (DOI: 10.1515/9781644699812).

The last is conventional bombing, meaning bombing with ordinary bombs and incendiary bombs that start fires rather than atomic bombs. Large-scale conventional bombing in the spring and summer of 1945 culminated in a 1,000-plane raid on August 14. Some squadrons dropped bombs after Japan announced its surrender (DOI: 10.1111/j.1467-7709.1995.tb00657.x). One study points out that incendiary bombing has almost faded from memory behind the name of the "atomic age" (DOI: 10.1017/s1557466014016969). The fact that there were four paths on the desk is what the documents show. Which path was open is the subject of debate in the following sections.

There is an order, but where is the moment of decision? — The form of approval

The Hiroshima strike order was sent to Potsdam in late July 1945. Historian Wellerstein claims it was subsequently retrieved and discarded. This is the passage translated and marked as a 「claim」 in a book review covering Wellerstein’s book. According to that review, the order listed the target as an 「'Army' city」. The book reads this retrieval as a sign of the document's sensitivity. According to the same review, the target description was deliberately written from the beginning to imply a military base. The word 「city」 was rarely used (DOI: 10.1162/jcws.r.1314).

The review translates a core sentence from the book as follows. 「There was no moment of deliberation and definitive decision by anyone, especially by Truman. The use of the atomic bomb was the accumulation of dozens of small decisions. Almost everyone involved in the project took it for granted that the weapon would be used」 (DOI: 10.1162/jcws.r.1314). The book argues that there was no moment of deliberation and definitive decision, and that the use of the atomic bomb was the accumulation of dozens of small decisions. The reviewer adds that this thesis is not new. As early as 1969, a Marxist historian wrote that 「the apparatus ruled」. In the reviewer's view, the use of the atomic bomb was an 「overdetermination」 where military, diplomatic, and domestic political reasons overlapped, and there was almost no dissenting opinion. Newly opened documents also show the thought process that led to that decision, they write (DOI: 10.1162/jcws.r.1314). This article knows of that argument only through the book review.

The review recounts two more instances of Truman's involvement. Secretary of War Henry Stimson succeeded in removing Japan's former capital, Kyoto, from the target list (DOI: 10.1162/jcws.r.1314). When photographs and casualty figures from Hiroshima and Nagasaki arrived at the White House, the review relates, Truman instructed that no further atomic bombs be used without his explicit approval. He told a cabinet member that he disliked the thought of killing 「all those kids」 (DOI: 10.1162/jcws.r.1314).

What Truman did not know is also in the documents. According to a 2012 study by historian Malloy, the fact that radiation makes victims ill and kills them for a long time was already raised in 1940 and was predictable by the time of the decision. Knowledge grew significantly through the human and animal experiments of the Manhattan Project. However, the compartmentalization and secrecy of General Leslie Groves, who directed the Manhattan Project, blocked that knowledge. Truman, Secretary of State James Byrnes, and Secretary of War Stimson were never ultimately reported on the fact that this weapon would continue to kill people even after its use (DOI: 10.1111/j.1467-7709.2012.01042.x). What decision-makers knew and what they did not know are among the few things that can be measured with documents.

Ways of reading the motives for approval vary by interpretation. Offner’s book, which critically re-evaluates Truman's diplomacy, views Truman as playing 「atomic poker」 at Potsdam to get ahead of the Soviet Union. Therefore, he brushed aside all proposals not to use the atomic bomb (DOI: 10.1515/9781503619616). A 2021 paper adds another factor to the dominant reason of avoiding casualties. It was the need to quickly return wartime production to a peacetime economy and hurry the reconstruction of Europe (DOI: 10.1080/09592296.2021.1883860). This article does not establish any of these motives as definitively Truman's. What is written in the diary is fear, the tone read by the paper introducing the diary is pessimism, and what is written in the order is the target.

Nine Days in Tokyo, and the Documents Opened Later

At 8:15 AM on August 6, 1945, it was Hiroshima. On the 8th, the Soviet Union tore up its neutrality pact with Japan and declared war (DOI: 10.4324/9781315606521-11; DOI: 10.1163/187656103793645261). From the 9th, fighting took place in Manchuria in northeastern China, which was guarded by the Japanese military (DOI: 10.4000/monderusse.7533). On that same 9th, the second bomb fell on Nagasaki. The Soviet military's operation lasted until September 5. Even after Japan surrendered, they moved down from island to island. In September, they stopped at a spot where Hokkaido was visible (DOI: 10.4000/monderusse.7533; DOI: 10.4324/9781315606521-11).

On August 9, the Supreme Council for the Direction of the War—the highest decision-making body in charge of the war map—met. Foreign Minister Shigenori Togo said that Soviet entry into the war was "completely unexpected." Historian Yukiko Koshiro, who has criticized Hasegawa, sets that remark against other documents. That same Togo had explained to the Emperor two months earlier, on June 8, that Soviet friendly neutrality was impossible. On August 19, 1944, the foreign minister of that time had mentioned the same difficulty. On December 8, 1941, an army general had anticipated the Soviet entry into war. On the 10th, Togo also met with Soviet Ambassador to Japan Yakov Malik, showing no hostility and speaking of friendship (DOI: 10.1353/jjs.2007.0066). Koshiro asks about the gap between what leaders knew and what they later claimed not to know. Her point is that the question is which document tells the truth (DOI: 10.1353/jjs.2007.0066).

Bernstein calls August 10 through 14 days that have "virtually vanished from modern memory." On the 10th, Japan offered to surrender on the condition that the Emperor system be guaranteed. On the 11th, the United States sent a deliberately ambiguous reply. The Japanese government was sharply divided over whether to continue the war. The Emperor intervened a second time and pushed toward surrender. A coup by some army officers trying to prevent the surrender almost succeeded. Bernstein believes that coup might have dragged out the war and brought on a third atomic bomb (DOI: 10.1111/j.1467-7709.1995.tb00657.x). At the meeting attended by the Emperor on August 14, the chiefs of staff of the army and navy argued for continuing the war. The final decision was left to the Emperor. An imperial decision is a ruling made directly by the Emperor when his ministers cannot reach a conclusion. The Emperor accepted the Potsdam Declaration (DOI: 10.4324/9780203844076-18). In a radio broadcast on the 15th, he spoke of "a new and most cruel bomb" (DOI: 10.1163/187656103793645261). He also told them to "bear the unbearable." On September 2, the surrender document was signed on the American battleship Missouri anchored in Tokyo Bay (DOI: 10.4324/9781315052038-6). According to one general history, more than 3 million Japanese and more than 10 million Chinese died in this war (DOI: 10.4324/9780203844076-18).

Up to this point is the sequence of events, and now comes the sequence in which documents were opened. In December 1946, the American magazine The Atlantic published "If the Atomic Bomb Had Not Been Used" by physicist Karl Compton, who had served as an advisor on wartime atomic energy. In February 1947, the American magazine Harper's published "The Decision to Use the Atomic Bomb" by Henry Stimson, who had been the Secretary of War. According to Bernstein, both pieces explained why alternatives would not have worked and sought to show that the bomb was necessary. These were writings that cemented the public belief of the time (DOI: 10.1111/j.1467-7709.1993.tb00158.x). Morton, in a 1957 paper, called Stimson's article "the first authoritative account." He named Stimson as the person more responsible than anyone else for advising the president (DOI: 10.2307/20031230). Truman's "500,000" in his postwar memoirs was seen in the previous section. Next comes the 1980 diary. According to Offner's book review, Soviet archives were opened after the Cold War ended (DOI: 10.1515/9781503619616). Hasegawa found in reports submitted to Stalin in January 1944 by an official equivalent to the Soviet vice foreign minister and in June by Ambassador to Japan Malik demands to reclaim the southern part of Sakhalin Island and the Kuril Islands. Both men cited Soviet security. They believed they could obtain them at a postwar conference without entering the war (DOI: 10.4000/monderusse.7533). On the Japanese side, there is the sourcebook Record of the End of the War, upon which Hasegawa relied. The main tone of the historical materials published there is "hope for Soviet neutrality." Koshiro rebutted that picture with "little-known documents" not published there (DOI: 10.1353/jjs.2007.0066). A book review reports that Wallerstein's book used many recently declassified documents (DOI: 10.1162/jcws.r.1314). Every time interpretations changed, newly opened documents were there. Yet interpretations diverge even over the same documents. That is the next section.

Three Interpretations — Orthodox, Revisionist, and Soviet Entry Theory

In February 1947, an article by Stimson published in Harper's marked the starting point of the orthodox interpretation. Kenneth Pyle, a historian who summarized the history of the atomic bomb debate, points out as its first characteristic that this interpretation was put forward by "the participants" (DOI: 10.1080/13439006.2015.1107260). This lineage grew thicker again in the 1990s. Robert Newman's 1995 book Truman and the Hiroshima Cult argues that the United States used the atomic bomb to end the war as quickly as possible and with the fewest casualties. This article read that book as a summary in the Society for Historians of American Foreign Relations (SHAFR) literature guide. The Strategic Bombing Survey is a U.S. military organization that investigated the effects of bombing immediately after the war. This survey concluded that Japan would have surrendered even without the atomic bomb, but Newman calls that conclusion a fabrication. He also maintains that the unconditional surrender principle did not significantly prolong the war. The use of the atomic bomb was neither racism nor a political maneuver targeting Stalin, but a sensible military decision (DOI: 10.1163/2468-1733_shafr_sim130130038). The introduction notes that diplomatic historian Wilson Miscamble's 2011 book directly clashes with the claim that the bomb targeted the Soviet Union. It also asks whether using this weapon was morally right (DOI: 10.1017/cbo9780511977336). A 2025 comprehensive chapter views the criticism that the unconditional surrender demand prolonged the war as a misreading of the situation. It records that the Japanese leadership accepted surrender only after the atomic bomb and the Soviet invasion of Manchuria (DOI: 10.1017/9781139104203.007). A 2019 paper arguing that the United States had grounds not to expect that guaranteeing the emperor would bring about a quick end to the war also stands in this line (DOI: 10.1163/24683302-20190005). The documents for this interpretation are invasion preparation records and the Japanese military's resolve for a decisive battle. The weakness is the "500,000" seen earlier. The points where the participants' memoirs conflict with 1945 documents lie at the starting point of this interpretation (DOI: 10.1080/01402399908437744).

The second is revisionism, which began in 1965. Pyle points out as its second characteristic that this interpretation was written during the Vietnam War era (DOI: 10.1080/13439006.2015.1107260). The name attached to that different motive is atomic diplomacy. Atomic diplomacy is the name given to the interpretation that the atomic bomb was also used as a diplomatic lever to keep the Soviet Union in check. There is a 2013 paper summarizing political economist and historian Gar Alperovitz's Atomic Diplomacy and The Decision to Use the Atomic Bomb. According to that paper, the two books read the atomic bomb as a weapon with political rather than military purposes. They also view the Cold War as having grown from the ashes of Hiroshima. This paper was published in an open-access small academic journal. It is an article defending Alperovitz by calling him a "great revisionist historian" (DOI: 10.4236/ahs.2013.22008). Alperovitz himself questioned the conventional wisdom again in 2016 with an article titled "The Bomb Didn't Win the War" (DOI: 10.1111/npqu.12044). Offner's "Atomic Poker" is also in this line (DOI: 10.1515/9781503619616). The documents for this interpretation are U.S.-Soviet diplomatic records before and after Potsdam. The weakness was persistently pointed out by the opposing side. Newman rejected the reading of political maneuvering, and Miscamble's book directly clashes with that claim (DOI: 10.1163/2468-1733_shafr_sim130130038; DOI: 10.1017/cbo9780511977336). One rhetorical study argues that the framework of caricature and the force of pushing things to the extreme pushed decision-makers to Hiroshima. At the same time, it challenges revisionist discourse (DOI: 10.1080/10570319809374614). Walker, who synthesized the literature, comments that both poles often relied on "strong assertions rather than strong evidence" (DOI: 10.1017/cbo9781139021760.006).

The third shifts the gaze to Tokyo and Moscow. Hasegawa wrote in 2007 that this debate had been "curiously narrow" and fixated solely on the U.S. leadership's decisions (DOI: 10.1017/s1557466007021742). His 2005 book Racing the Enemy brought the United States, the Soviet Union, and Japan into a single story (DOI: 10.1515/9781644699812). In a 2011 paper, he makes his conclusion clear. Stalin's goal was to secure the spoils promised at Yalta through entry into the war. Japan's reliance on Soviet neutrality helped him. Ultimately, Soviet entry played a more decisive role than the atomic bomb in Japan's decision to surrender (DOI: 10.4000/monderusse.7533). In a 2023 dialogue, he refutes both premises of the conventional wisdom: that the atomic bomb was the only option to avoid an invasion, and that the bomb worked immediately on surrender. He cites revenge as a hidden third motive (DOI: 10.1017/s1557466023028681). The documents for this interpretation are Soviet diplomatic records and Japanese meeting records. The weakness came from the Japanese document side. A 2003 study frames the atomic bomb and Soviet entry as a "twin shock" that compelled the emperor's decision. It views the real shock of Hiroshima as the fact that the United States had built a weapon that Japanese scientists had said was impossible (DOI: 10.1163/187656103793645261). In Bernstein's re-read interrogation of the Strategic Bombing Survey, Hisatsune Sakomizu, the Chief Secretary of the Japanese Cabinet at the time, emphasized the atomic bomb as the reason for surrender. This was the interrogation on December 11, 1945 (DOI: 10.4324/9781315237145-17). Koshiro refutes Hasegawa's premise itself with the documents from the previous section — namely, the premise that "most leaders clung naively to Soviet neutrality" (DOI: 10.1353/jjs.2007.0066). A 2012 study argues that neither of the two shocks tells the whole story, suggesting that the conservative ruling class's fear of social revolution accelerated the decision to end the war (DOI: 10.1080/07075332.2012.742450).

The fourth place belongs to Pyle. Following the orthodox view, revisionism, and Japanese responsibility theory, he views the momentum created by Roosevelt's unconditional surrender policy as the decisive factor. This policy allegedly provoked the unconditional resistance of the Japanese military. By 1945, it was deeply entrenched in American public opinion (DOI: 10.1080/13439006.2015.1107260). A 1983 rhetorical study made the same point earlier (DOI: 10.1080/00335638309383664). The opposing side consists of the 2025 chapter and Newman seen earlier (DOI: 10.1017/9781139104203.007; DOI: 10.1163/2468-1733_shafr_sim130130038). Walker observed in 2013 that academia was moving "perhaps decisively" away from the poles toward a balanced narrative (DOI: 10.1017/cbo9781139021760.006). Bernstein's work serves as an exemplar of that middle ground. While dismantling "500,000," he similarly doubted the Strategic Bombing Survey's conclusion of early surrender (DOI: 10.1080/01402399908437744; DOI: 10.4324/9781315237145-17). Each of the three interpretations has its own documents, and the points where they fail to explain the opponent's documents remain the dividing lines.

Where Agreement Lies and Where They Still Split — The Place of "Had Things Not Been So"

In 1995, a controversy that erupted when the Smithsonian National Air and Space Museum in the United States attempted to exhibit the Enola Gay, the bomber that dropped the atomic bomb on Hiroshima, brought this debate to the front pages of newspapers (DOI: 10.1017/cbo9781139021760.006; DOI: 10.1017/s1557466014016969). Newman, on the orthodox interpretation side, called criticism of the atomic bomb that grew after the 1960s the "Hiroshima cult" in the same year (DOI: 10.1163/2468-1733_shafr_sim130130038). A file summarizing the history of the atomic bomb debate records that no school of thought has reached a consensus (DOI: 10.1080/13439006.2015.1107260). Still, there are areas where they overlap.

The areas where the documents read by this article overlap are four. First, Bernstein did not find "500,000" in 1945 documents, and a 1995 writing that advocated high estimates became the target of his criticism (DOI: 10.1080/01402399908437744; DOI: 10.1111/0149-0508.00119). Second, according to Malloy's research, decision-makers were not briefed on the lasting effects of radiation (DOI: 10.1111/j.1467-7709.2012.01042.x). Third, the atomic bomb and Soviet entry into the war acted together. An orthodox-side 2025 chapter also lists the two side by side. A 2003 study also calls them the "twin shocks" (DOI: 10.1017/9781139104203.007; DOI: 10.1163/187656103793645261). Fourth, the Japanese leadership remained divided to the end and the decision fell to the emperor (DOI: 10.4324/9780203844076-18; DOI: 10.1111/j.1467-7709.1995.tb00657.x).

The areas where they split gather on counterfactuals. A counterfactual is reasoning that examines the outcome under the condition "had things not been so". First, which shock was heavier? Hasegawa points to the Soviet entry into the war (DOI: 10.4000/monderusse.7533). A 2003 study places the two as twins (DOI: 10.1163/187656103793645261). In a Strategic Bombing Survey interrogation in December 1945, Chief Cabinet Secretary Sakomizu emphasized the atomic bomb (DOI: 10.4324/9781315237145-17). Counterarguments by historians that the atomic bomb was more decisive were not confirmed as original sources within the scope of literature read by this article. A 2007 guide walks through ten issues of this debate and primary documents (DOI: 10.7312/kort13016). Second, would they have surrendered before November if there had been no atomic bomb, no Soviet entry into the war, and no invasion? The Strategic Bombing Survey said yes. Bernstein examined how that conclusion was manufactured. Newman called it a fabrication (DOI: 10.4324/9781315237145-17; DOI: 10.1163/2468-1733_shafr_sim130130038). Third, what if the imperial system had been guaranteed in advance? A 2019 paper summarizes that revisionists have repeatedly argued so. And it answers that there were legitimate grounds for the United States not to expect that (DOI: 10.1163/24683302-20190005). It does not answer the counterfactual itself. Fourth, if the coup on August 14 had succeeded, would a third atomic bomb have been dropped? Bernstein considers it possible (DOI: 10.1111/j.1467-7709.1995.tb00657.x). This article answers none of these four questions.

Ethical judgments also split. Hasegawa views the U.S. use of the atomic bomb as a war crime. However, he says it must be understood within the context of Japan's responsibility for starting an aggressive war and committing atrocities (DOI: 10.1017/s1557466023028681). Newman views it as a sensible military decision (DOI: 10.1163/2468-1733_shafr_sim130130038). Miscamble makes whether it was morally right the question of his book (DOI: 10.1017/cbo9780511977336). The file views historians' judgments as relative to the era and position from which they write (DOI: 10.1080/13439006.2015.1107260). Bernstein warns of the dangers of relying on postwar memoirs and interviews. His point is to prioritize contemporary documents. Otherwise, policy-makers write history with memoirs favorable to themselves (DOI: 10.1080/01402399908437744).

What Truman decided that day remains as follows. Both the strike order and the instruction to halt further use remain, according to what the book review conveys. One historian argues there was no moment of decision. This article knows that argument only through a book review. As for why Japan surrendered, the scale weighing the two shocks is still shaking. The single line this article will take away is one: Each time documents open, the questions grow.

Source Papers

• "Today Has Been A Historical One: Harry S Truman's Diary of the Potsdam Conference" (1980) — DOI: 10.1111/j.1467-7709.1980.tb00351.x — The diary from July 16–30 found in the Charles Ross papers, unpublished and uncited before its 1980 release. "Machines are several centuries ahead of morals."
• "Racing the Enemy" (2022 reprint; original 2005) — DOI: 10.1515/9781644699812 — Hasegawa's monograph. The April abrogation of the neutrality pact and Truman's inauguration, Stalin's mediation proposals and war preparations, Tokyo's peace faction versus the war party.
• "A Reexamination of the 'Shock of Hiroshima'" (2003) — DOI: 10.1163/187656103793645261 — August 6 at 8:15 AM, the August 8 Soviet entry, the "twin shocks", the August 15 broadcast about the "new and most cruel bomb", and Japanese scientists judging it impossible on July 21.
• "The rhetoric of 'unconditional surrender' and the decision to drop the atomic bomb" (1983) — DOI: 10.1080/00335638309383664 — Casablanca 1943, a rhetorical analysis of how a slogan became a policy-constraining watchword.
• "Who Really Made the Decision to Drop the First Atomic Bomb on Hiroshima?" (2015) — DOI: 10.4324/9781315664637-9 — The July 26 text of the Potsdam Declaration, "prompt and utter destruction", and Tokyo's non-response.
• "Reforming Education in Postwar Japan" (2014) — DOI: 10.4324/9781315052038-6 — The declaration's "no deviation, no alternative, no delay", the August 15 "endure the unendurable", and the Missouri on September 2.
• "Soviet policy toward Japan during World War II" (2011) — DOI: 10.4000/monderusse.7533 — Hasegawa's paper. The August 9 – September 5 operations, Yalta spoils, Tehran promises, the 1944 Maisky-Malik memos, Stalin being caught off guard at Potsdam, and Soviet entry being more decisive than the atomic bomb.
• "Reconsidering Truman's claim of 'half a million American lives'" (1999) — DOI: 10.1080/01402399908437744 — Bernstein. 500,000 absent from 1945 documents, the ghostwriting process of the memoirs, and the contemporary documents-first principle.
• "A postwar myth: 500,000 U.S. lives saved" (1986) — DOI: 10.1080/00963402.1986.11459388 — Bernstein. Planners during and immediately after the war used much lower figures.
• "Reconsidering 'Invasion Most Costly'" (1999) — DOI: 10.1111/0149-0508.00119 — Bernstein. A critique of the high-casualty claims made by Giangreco and Allen in 1995.
• "Recent Literature on Truman's Atomic Bomb Decision" (2013) — DOI: 10.1017/cbo9781139021760.006 — Walker. Polarized "strong assertions", the Enola Gay, the shift toward the middle, and the either-or framework of traditional interpretation.
• "Unconditional Surrender and the American Case Against the Modification" (2019) — DOI: 10.1163/24683302-20190005 — The American basis for arguing that guaranteeing the emperor would not have ensured a prompt end to the war.
• "Internal and External Risks to Japan's Northern Territories Policy" (2016) — DOI: 10.4324/9781315606521-11 — The August 8 declaration of war, Manchurian and Kuril operations, stopping short of Hokkaido, and the Yalta promises.
• "Understanding the Atomic Bomb and the Japanese Surrender" (1995) — DOI: 10.1111/j.1467-7709.1995.tb00657.x — Bernstein. The August 10 conditional proposal, August 11 ambiguous reply, division, second intervention, aborted coup, third atomic bomb, and August 14 raids by 1,000 planes.
• "Alex Wellerstein, The Most Awful Responsibility" (2026, book review) — DOI: 10.1162/jcws.r.1314 — A review of Wellerstein's book. Citing the thesis from page 308 that "there was no single moment of decision", "overdetermination" (reviewer), December 1945 polling under 5%, recall of strike orders ("Wellerstein claims"), exclusion of Kyoto, and instructions banning further use.
• "The Columbia Guide to Hiroshima and the Bomb" (2007) — DOI: 10.7312/kort13016 — Kort's monograph. An overview of the debate, ten issues, and a guide to primary documents.
• "Bombs Bursting in Air" (2014) — DOI: 10.1017/s1557466014016969 — Selden. The surrender question is the most fiercely debated, while incendiary bombings have vanished from memory.
• "'A Very Pleasant Way to Die': Radiation Effects and the Decision" (2012) — DOI: 10.1111/j.1467-7709.2012.01042.x — Malloy. Radiation effects were anticipated, but Truman, Byrnes, and Stimson were not briefed.
• "Another Such Victory" (2002) — DOI: 10.1515/9781503619616 — Ofner's monograph. Potsdam's "atomic poker", and documents released after the end of the Cold War.
• "Creation by Destruction" (2021) — DOI: 10.1080/09592296.2021.1883860 — Factors of economic reconversion and European reconstruction.
• "Reply to Hasegawa" (2007) — DOI: 10.1353/jjs.2007.0066 — Koshiro. 1941, 1944, and June 8 records, the August 9 "completely unexpected event", the August 10 Malik meeting, and documents outside the Shūsen Shiroku (Records of the End of the War).
• "The End of the War" (2010) — DOI: 10.4324/9780203844076-18 — The August 14 Imperial Conference, chiefs of staff arguing to continue the war, the emperor's acceptance, and 3 million to 10 million deaths.
• "Seizing the Contested Terrain of Early Nuclear History" (1993) — DOI: 10.1111/j.1467-7709.1993.tb00158.x — Bernstein. Articles by Compton in 1946 and Stimson in 1947.
• "The Decision to Use the Atomic Bomb" (1957) — DOI: 10.2307/20031230 — Morton. Framing Stimson's 1947 writing as the "first authoritative explanation".
• "Hiroshima and the Historians: History as Relative Truth" (2015) — DOI: 10.1080/13439006.2015.1107260 — Fey. Four schools, the inertia of unconditional surrender policy, and no consensus.
• "Truman and the Hiroshima Cult" (1995; SHAFR summary 2017) — DOI: 10.1163/2468-1733_shafr_sim130130038 — Newman. The "fabrication" of the USSBS conclusions, sensible military decision (in the summarizer's phrasing), and the "Hiroshima Cult".
• "The Most Controversial Decision" (2011) — DOI: 10.1017/cbo9780511977336 — Miscamble's monograph. Direct rebuttal of the Soviet-targeting thesis, and questions of moral justification.
• "Surrender in a War of Extremes, 1937–1945" (2025) — DOI: 10.1017/9781139104203.007 — Rebutting criticisms that unconditional surrender prolonged the war, and pointing to the bomb plus Soviet invasion as driving acceptance.
• "Reclaiming Realism for the Left: Gar Alperovitz" (2013) — DOI: 10.4236/ahs.2013.22008 — Summary of Alperovitz's thesis (open-access small scholarly journal, supportive in nature).
• "Obama's Hiroshima Visit Is a Reminder that Atomic Bombs Weren't What Won the War" (2016) — DOI: 10.1111/npqu.12044 — Opinion piece by Alperovitz himself.
• "Reassessing Truman, the bomb, and revisionism" (1998) — DOI: 10.1080/10570319809374614 — Rhetorical critique of revisionist discourse.
• "The Atomic Bombs and the Soviet Invasion: What Drove Japan's Decision to Surrender?" (2007) — DOI: 10.1017/s1557466007021742 — Hasegawa. The debate was narrow and US-centric.
• "Conversations with Tsuyoshi Hasegawa" (2023) — DOI: 10.1017/s1557466023028681 — Rebutting two premises, multiple motivations, a war crime but within the context of Japanese responsibility.
• "Compelling Japan's Surrender Without the A-bomb, Soviet Entry, or Invasion" (2017 reprint) — DOI: 10.4324/9781315237145-17 — Bernstein. Re-examining the USSBS early-surrender counterfactual, and the December 11 interrogation of Sakomizu.
• "The Specter of Revolution: Reconsidering Japan's Decision to Surrender" (2012) — DOI: 10.1080/07075332.2012.742450 — The factor of fear of social revolution.