In his press release, President Truman gives one reason for using the atomic bomb on Japan. The reason that he gives is simply that the Japanese had not surrendered when given the chance to do so. Truman cites the Potsdam Declaration in which the Allies demanded unconditional surrender. He points out that the Japanese rejected the demand. Therefore, he says, the US was going to use every weapon available to it in order to defeat Japan. The atomic bomb was one such weapon. Truman's press release does not dwell on the decision to drop the bomb. It does not try to justify it. It simply assumes that, in war, you use everything you have to win.