Why was the decision by President Truman to drop the atomic bomb controversial?

Answer 1

Humanists claim that most of the casualties were civilians. They were right but in some point the President might have the right decision. Going in Japan's main land would take too long and the casualties would be worse. X-Day would have been THE worst decision the U.S. would have made during WWII. It had already been decided that chemical weapons would be used in the invasion of Japan if they resisted as they had on the final islands (and nobody doubted they would resist). Which was potentially more controversial: use of the atomic bomb or use of chemical weapons?

Also 23 atomic bombs were scheduled to be dropped on Japan in 1945 (production had not yet been determined for 1946), not just the 2 that were actually used. This meant that BOTH atomic bombs and chemical weapons would certainly be used in Japan had they not surrendered and we had invaded!!!

All these decisions had already been made prior to FDR's death (the atomic bomb only being contingent on a successful test) and Truman simply decided to continue all of FDR's policies unchanged. The only real decision Truman ever made himself on the atomic bomb during WW2 was that when Japan indicated on August 14 that they would surrender was to order the end of the bombing of Japan, which caused the third atomic bomb for August to be returned from San Francisco on August 18 to Los Alamos instead of being flown to Tinian.

Answer 2

He knew that many people was going to die.