Truman never ordered the use of the atomic bombs—but he did order atomic bombings to be stopped

When it comes to marking anniversaries of the atomic bomb, there are a few obvious choices. July 16, 1945, was the date of the Trinity test, the first nuclear explosion, and has been used by some as an arbitrary beginning for the Anthropocene Epoch, the age of humans. August 6, 1945, was the date of the atomic bombing of Hiroshima. The bombing of Nagasaki, on August 9, is often overlooked as merely the “second” atomic bomb used in combat.

It is well and proper that these dates are the ones that garner the most attention. But there is another date that perhaps deserves to be added: August 10, 1945. For that is the date that the use of atomic bombs in war stopped—for reasons that are worth remembering 80 years later.

While he never made a singular “decision to use the bomb,” as the common (but ahistorical) telling of the events of the summer of 1945 would have it, President Harry Truman was aware that the first atomic bomb would be used sometime in early August. Gen. Leslie Groves, the head of the Manhattan Project and the person perhaps most individually responsible for the making and use of atomic bombs, later characterized Truman’s decision as “one of noninterference—basically, a decision not to upset the existing plans.”^[1]

But the exact boundaries between what Truman did and did not know about the “existing plans” are not entirely clear. Among other areas of possible confusion, it is not clear that Truman understood the schedule of the atomic bombings—even though this is one of the few operational details he had inquired about personally, while at the Potsdam Conference in late July 1945, after he had received the positive news about the success of the Trinity test.

Truman’s conduit for information about the atomic bomb plans was his Secretary of War, Henry Stimson. Stimson passed an inquiry about the “schedule” along to his contacts in Washington, DC. He received a swift reply, one that was seemingly direct:

First one of tested type should be ready at Pacific base about 6 August. Second one ready about 24 August.^[2]

Stimson read this to Truman. It would appear to give clear information about the planned bombing. But careful and informed readers will immediately see the problem: It is only the schedule of the “tested type” of atomic bomb, which is to say, the plutonium-fueled implosion design that had been detonated at Trinity. There was another atomic bomb design, the gun-type, uranium-fueled design (Little Boy) that was considered such a sure-thing that it did not require being tested. Truman had been told that there were two types of bombs being developed back in April 1945, but by the summer of 1945 all discussions of the atomic bomb treated it as a singular object (“the atomic bomb”), and the operational details focused on the first combat use of the bomb. It appears entirely possible that Truman did not understand that there would be two atomic bombs in early August, with a second plutonium bomb ready a few weeks later.

The only formal “strike order” on the atomic bomb was drafted by General Groves on July 24, and approved by Secretary Stimson and Chief of Staff George Marshall on July 25 (and not Truman). It is not clear that Truman himself ever saw it directly prior to it being issued, but if he had, it would hardly clarify the issue. The first part of the order specified that the “first special bomb” could be dropped “as soon as weather will permit visual bombing after about 3 August 1945 on one of the targets: Hiroshima, Kokura, Niigata and Nagasaki.” The only reference to the fact that there would be more to come was in its broad second part: “Additional bombs will be delivered on the above targets as soon as made ready by the project staff. Further instructions will be issued concerning targets other than those listed above.”^[3]

Truman’s main concern about the “schedule” seems to have been that the first bomb not be used while the Potsdam Conference was still ongoing, a product of his desire to disentangle the atomic bomb from any discussions with the Soviet Union (which, he incorrectly believed, was almost entirely ignorant about the Anglo-American atomic project). Even if he had known the true planned schedule, though, it still would have been somewhat misleading: the original goal was to have the gun-type weapon ready to use August 1-3, and the first plutonium bomb ready to use on August 10—a gap of at least one week.

As it happened, the first atomic strike mission, with Hiroshima as its primary target, was delayed until August 6, because the late summer weather in Japan was too cloudy and overcast to allow for visual bombing. Truman, on-board the USS Augusta traveling across the Atlantic Ocean, was overjoyed at the news of the bombing. “This is the greatest thing in history,” he announced to the crew, and he later gave a press conference to the reporters on the ship, reading a version of the official announcement that had come out under his name (which he had no role in writing) earlier that day:

Sixteen hours ago an American airplane dropped one bomb on Hiroshima, an important Japanese Army base. That bomb had more power than 20,000 tons of T.N.T. It had more than two thousand times the blast power of the British “Grand Slam” which is the largest bomb ever yet used in the history of warfare. … It is an atomic bomb. It is a harnessing of the basic power of the universe. The force from which the sun draws its power has been loosed against those who brought war to the Far East.^[4]

The official statement threatened that more would be used if the Japanese did not accept the demand of unconditional surrender: “If they do not now accept our terms they may expect a rain of ruin from the air, the like of which has never been seen on this earth.”

Truman did not return to the White House until late in the evening on August 7. On the morning of August 8, he received a briefing from Stimson, with the press corps present, on the damage at Hiroshima. The now-famous aerial photo of the destroyed city was only available that day, as the smoke had finally cleared enough to allow American planes to photograph the wreckage. This was released concurrent with the first Japanese reports of destruction and accompanying estimates of casualties in the tens and even hundreds of thousands.^[5]

Stimson wrote in his diary afterwards that after his briefing, Truman felt “the terrible responsibility that such destruction placed upon us here and himself.”^[6]

Even while Truman and Stimson were meeting, the second atomic bombing mission was beginning, on the other side of the Earth. The weather report for August 10 had been unfavorable, and so the local authorities at Tinian, the launch-pad for the bombing operations, opted to accelerate the schedule, assembling the first implosion bomb, Fat Man, a day earlier than planned. The second atomic bombing mission was far more ill-fated that the first one, rife with both technical and human errors, but still managed to drop the bomb onto Nagasaki on the morning of August 9.

If Truman said anything about the Nagasaki mission immediately, there is no record of it. It is, again, not at all clear that he even knew it was going to happen. He had been alerted just prior to the Hiroshima strike that it was imminent, but no such message appears to have been sent for the second one. As the strike order had indicated, bombs after the first one could be dropped at will, once available—and it is not clear that Truman was aware of how little control any political leaders had over the use of the bomb after the first one. It may have also been overshadowed by other momentous news: during the night of August 8/9, the Soviet Union had declared war on Japan, and begun its invasion of Manchuria.

On the morning of August 10, several things happened. Overnight, the Japanese had sent an offer of surrender, saying that they would accept the terms of the Potsdam Declaration, “with the understanding that the said declaration does not comprise any demand which prejudices the prerogatives of His Majesty as a sovereign ruler.” This provoked considerable discussion in Washington, as this felt like a “condition”: The Japanese were carving out a special space for their Emperor. There were some in Truman’s orbit who were happy to accept this particular condition, but Secretary of State James Byrnes and Truman himself were insistent that truly unconditional surrender was required.^[7]

At some point during the day—and we have no contemporary evidence of when exactly this happened—General Groves hand-delivered a message to his boss, Chief of Staff Marshall. It was short and to the point:

The next bomb of the implosion type had been scheduled to be ready for delivery on the target on the first good weather after 24 August 1945. We have gained 4 days in manufacture and expect to ship from New Mexico on 12 or 13 August the final components. Providing there are no unforeseen difficulties in manufacture, in transportation to the theatre or after arrival in the theatre, the bomb should be ready for delivery on the first suitable weather after 17 or 18 August.^[8]

This was the “third shot,” the next plutonium bomb, whose core was at that moment being cast at Los Alamos. The exact timeline is unclear, and attempts by Groves to clarify it later are suspiciously self-serving. But the bottom of the memo contains a momentous line, written in Marshall’s handwriting and followed by his signature: “It is not to be released over Japan without express authority from the President.”

On that afternoon, Truman held a meeting with his full cabinet, telling them about the developments with the Japanese. Secretary of War Henry Stimson brought up the idea that perhaps some sort of armistice should be put into place while the Japanese received and reacted to the American rejection of their surrender offer, citing “the growing feeling of apprehension and misgiving as to the effect of the atomic bomb even in our own country,” according to the diary entry of the Secretary of the Navy, James Forrestal.^[9] The idea was rejected by Truman, as until the Japanese gave a formal offer of surrender, “the war was still on,” Stimson wrote later in his own diary.^[10]

But when Truman rejected Stimson’s suggestion to halt all bombing, he informed the group that “there would be no further dropping of atomic bombs,” according to Forrestal’s diary.^[11] In the diary of another participant, Secretary of Commerce Henry Wallace, we get a more vivid account of Truman’s explanation:

Truman said he had given orders to stop atomic bombing. He said the thought of wiping out another 100,000 people was too horrible. He didn’t like the idea of killing, as he said, “all those kids.”^[12]

Because we do not have an exact timeline of Groves’ discussion with Marshall, it is hard to know the exact sequence of events. Did Truman give an order to stop atomic bombing before any news reached him about another atomic bomb being ready for use in about a week? Or did he get this information and then give the order? In a sense, it does not matter, except to point out two things: Truman took explicit credit for ordering the stopping of the atomic bombing, and; his explicit justification was not rooted in diplomatic wrangling, political considerations, or grand strategy, but was an emotional and moral response to the killing of non-combatants.

It is not the only time that Truman expressed such sentiments. That December, well after the atomic bombs had been credited with winning the war, Truman gave a speech, written by his own hand, in which he described the use of the atomic bombs as “the most terrible decision a man ever had to make.” While he justified the use of the atomic bombs, as he always did throughout his life, the language he used was again dripping with moral revulsion: The atomic bomb was “the most terrible of all destructive forces for the wholesale slaughter of human beings,” and he admitted to be being troubled by “blotting out women and children and non-combatants.”^[13] Years later, on his final day in office, Truman would take the time to write a private letter expressing his view that the atomic bomb “is far worse than gas and biological warfare because it affects the civilian population and murders them by the wholesale.”^[14]

Murder, slaughter, “all those kids”: This is not the language that anyone defending the atomic bombings today would use when talking about the weapons. This is moral language; it is “taboo” language. As the political scientist Nina Tannenwald, who has written the most on the idea of the “nuclear taboo,” would emphasize, this is the kind of language that promotes the idea that nuclear weapons are not usable weapons not because of mutually assured destruction, but because they are immoral. It is a language that emphasizes suffering, the distinctions between combatants and non-combatants, and the particular role that children play in the moral calculus of war.^[15]

There is much more that can be said about Truman’s views towards the atomic bomb, and his understanding of what was meant to happen at Hiroshima. The argument of my forthcoming book is that Truman did not truly understand that Hiroshima was a city, and did not anticipate the high numbers of non-combatant casualties. He would have learned these things conclusively by August 8. But his ignorance about the schedule of the bombings meant that the second use of the bomb, on Nagasaki, would have come as a surprise. This appears, I argue, to be why he ordered a halt to the atomic bombings shortly afterwards—perhaps as a result of being told another bomb would be soon shipped to the Pacific theatre.

Whatever the exact sequence of events, the takeaway from August 10, 1945, is that it was when Truman asserted presidential control over the question of nuclear use for the first real time, and he did so in order to stop further nuclear weapons use, and he did so for explicitly moral reasons. This “stop order,” and not the original “use order” of the atomic bombs, is where the idea of presidential unilateral control over nuclear weapons originated, and would be further reinforced by Truman many times over the course of his presidency. (Whether we find this an appropriate or reassuring policy today is a separate question.)

Truman always argued that the atomic bombings of Hiroshima and Nagasaki were justified. He also had little tolerance for other people second-guessing the outcomes of World War II. Despite this, he nonetheless always retained a sense of horror at their consequences. He is sometimes erroneously portrayed as callous about the suffering of the Japanese; his calling of J. Robert Oppenheimer a “cry-baby” when the latter professed his own sense of guilt is, in my view, more about his annoyance at Oppenheimer claiming responsibility for a burden that Truman believed fell upon himself than about any callousness toward victims.

Truman deserves credit for the first use of the atomic bomb in war. But he also deserves some credit for the fact that they have not been used in that way since. Truman never gave an explicit order to use the atomic bomb—but he did give the order that stopped them from being used again. Truman’s views on the atomic bombings were more subtle than they at first appear. If he truly believed they were a necessary evil, and he may have, he never lost sight of the fact that necessary evils may still be evil.

Notes

[1] Leslie R. Groves, Now It Can Be Told (Harper & Row, 1962), 265. For more on Truman’s individual role, see esp. J. Samuel Walker, Prompt and Utter Destruction: Truman and the Use of Atomic Bombs Against Japan, revised edition (University of North Carolina Press, 2004), and Alex Wellerstein, The Most Awful Responsibility: Truman and the Secret Struggle for Control of the Atomic Age (HarperCollins, forthcoming 2025).

[2] George Harrison to Henry L. Stimson, WAR 37350 (23 July 1945) (but not received at Potsdam until July 24), Correspondence (“Top Secret”) of the Manhattan Engineer District, 1942–1946, microfilm publication M1109, Washington, DC, National Archives and Records Administration, 1980.

[3] Thomas Handy to Carl Spaatz (25 July 1945), Correspondence (“Top Secret”) of the Manhattan Engineer District, 1942–1946, Roll 1, Target 6, Folder 5B.

[4] William M. Rigdon, Log of the President’s Trip to the Berlin Conference (August 1945), Log of the President’s Trip to the Berlin Conference, Harry S. Truman Presidential Library, Rose A. Conway Papers, Subject Files, “President Truman’s Travel Logs, 1945,” NAID: 79443350, 49–50.

[5] E.g., “Atomic Bomb Destroyed 60% of Hiroshima; Pictures Show 4 Square Miles of City Gone; B-29 Dropped New Explosive by Parachute,” New York Herald Tribune (8 August 1945), A1.

[6] “Memorandum of Conference with the President, August 8, 1945 at 10:45am,” in Stimson diary (8 August 1945), Henry Lewis Stimson Papers (MS 465), Manuscripts and Archives, Yale University Library.

[7] For details on the delicate negotiations, and the Japanese and Soviet sides of this, see esp. Tsuyoshi Hasegawa, Racing the Enemy: Stalin, Truman, and the Surrender of Japan (Harvard University Press, 2005.).

[8] Leslie R. Groves to George C. Marshall (10 August 1945), National Archives and Records Administration, Archives II, RG77, General Correspondence, “25 Q,” NAID: 6874336.

[9] James Forrestal diary (10 August 1945), James V. Forrestal Papers, MC051, Princeton University Library, Special Collections, Series 5, Subseries 5A, “Diaries, Originals.”

[10] Stimson diary (10 August 1945), Stimson Papers.

[11] Forrestal diary (10 August 1945), Forrestal Papers.

[12] Wallace diary (10 August 1945), reprinted in The Price of Vision: The Diary of Henry A. Wallace, 1942–1946 (Houghton Mifflin, 1973), 474.

[13] “Handwritten draft of Gridiron Dinner Remarks” (December 1945) Truman Presidential Library, President’s Secretary’s File, Speech Files, Presidential Speeches—Longhand Notes File, October–December 1945, NAID: 183567528.

[14] Truman to Thomas E. Murray (19 January 1953), Truman Presidential Library, President’s Secretary’s File, General Files, “Atomic Bomb,” NAID: 313172656.

[15] Nina Tannenwald, The Nuclear Taboo: The United States and the Non-Use of Nuclear Weapons Since 1945 (Cambridge University Press, 2007).