It could be argued that the decision to use the atomic bomb was actually made on 6 December 1941, when the first money was approved to fund its development. At the time, American leaders assumed the new invention would be a legitimate weapon in the war, and they never questioned that assumption afterward.
Although President Franklin D. Roosevelt's key advisers on the project concluded in May 1943 that the first operational bomb should be dropped on Japan, the choice of targets really did not receive systematic attention until two years later. A special Target Committee for the manhattan Project began meeting in April 1945, and by the next month it had selected a shortlist of cities including Kyoto and Hiroshima. On 31 May, a blue-ribbon Interim Committee appointed by Secretary of War Henry L. Stimson began meeting to discuss how best to use the new weapon. A suggestion made at lunch to try a warning and noncombat demonstration was quickly rejected for many practical reasons, and the committee recommended that the bomb be dropped without warning on a target that would make the largest possible psychological impression on as many inhabitants as possible.
Eventually, military planners came up with a target list of Hiroshima, Kokura, Kyoto, and Nigata. Stimson persuaded the planners to substitute Nagasaki for the shrine city of Kyoto and then presented the list to President Harry S Truman in late July. Truman approved the directive without consulting anyone else and wrote in his diary that the bomb would be used between 25 July and 10 August. The new weapon offered the possibility of ending the war sooner, and he had no compelling reason not to employ it. Despite some historians' claims to the contrary, there was no reliable evidence of any imminent Japanese collapse or surrender. Although some leaders did perceive a display of the atomic bomb's power as a potential tool to intimidate the Soviet Union in the future, this was a secondary benefit of its employment and not a factor in operational decisions.
No single government document shows Truman's decision to use the bomb, but there were two relevant military directives from the Joint Chiefs to the U.S. Army Air Forces. The first, to General Henry "Hap" Arnold on 24 July, designated the four possible targets. The next day, a similar order to General Carl Spaatz, who was commanding strategic air forces in the Pacific, added a date: "after about 3 August 1945." That document also directed that other bombs were to be delivered against targets as soon as they were ready. On the basis of these orders, Spaatz selected Hiroshima and then Kokura to be the targets for the first and second atomic missions. (Cloud cover on the day of the second raid caused the shift to the secondary target of Nagasaki.)
Some critics have questioned why there was not more deliberation about whether to use the terrible new weapon. The main concern for decision-makers was to win the war quickly while avoiding a bloody invasion or losing public support for unconditional surrender. Under the conditions in 1945, which had already produced fire raids that had killed far more Japanese civilians than did the attacks on Hiroshima and Nagasaki, no U.S. president or general could have failed to employ the atomic bomb.
Conrad C. Crane
Bernstein, Barton. "The Dropping of the A-Bomb." Center Magazine (March-April 1983), 7–15.; Kagan, Donald. "Why America Dropped the Bomb." Commentary 100 (September 1995): 17–23.; Merrill, Dennis. The Decision to Drop the Atomic Bomb on Japan. Vol. 1, Documentary History of the Truman Presidency. Bethesda, MD: University Publications of America, 1995.; Wainsrock, Dennis D. The Decision to Drop the Atomic Bomb. Westport, CT: Praeger, 1996.; Walker, J. Samuel. Prompt and Utter Destruction: Truman and the Use of Atomic Bombs against Japan. Chapel Hill: University of North Carolina Press, 1997.