As Truman hurried back to the United States from Potsdam, he faced the final decision of whether to utilize the new atomic weapons. Truman had several committees of experts that were advising him on the matter. One such committee was the Interim Committee. This committee was composed of top scientists, and military and government officials including Secretary of War Henry Stimson, General George C. Marshall, Enrico Fermi, and J. Robert Oppenheimer. The committee unanimously recommended that the atomic bomb be used against Japan as soon as possible and without warning. The only other choice was to stage an invasion of the Japanese islands, and the cost in lives for both sides was too staggering — even compared to the losses expected from an atomic blast.

Not all scientists and political advisors, however, were in favor of...