Reply #167: Correct. Actually James Byrnes mostly made the decision...

[Junkdrawer]

Byrnes was also one of Truman's advisors on the atomic bomb. He was Truman's representative on the Interim Committee, a group formed to study post-war nuclear issues but which also briefly discussed how the a-bomb should be used on Japan.

Byrnes had his own ideas about the a-bomb. In addition to defeating Japan, he wanted to keep Russia from expanding their influence in Asia; he also wanted to restrain them in Europe. Manhattan Project scientist Leo Szilard met with Byrnes on May 28, 1945. Szilard later wrote of the meeting,


" was concerned about Russia's postwar behavior. Russian troops had moved into Hungary and Rumania, and Byrnes thought it would be very difficult to persuade Russia to withdraw her troops from these countries, that Russia might be more manageable if impressed by American military might, and that a demonstration of the bomb might impress Russia." (Spencer Weart and Gertrud Szilard, Leo Szilard: His version of the Facts, pg. 184).


http://www.doug-long.com/byrnes.htm