2 Quotes

Eisenhower wrote in his memoir The White House Years:
In 1945 Secretary of War Stimson, visiting my headquarters in Germany, informed me that our government was preparing to drop an atomic bomb on Japan. I was one of those who felt that there were a number of cogent reasons to question the wisdom of such an act? During his recitation of the relevant facts, I had been conscious of a feeling of depression and so I voiced to him my grave misgivings, first on the basis of my belief that Japan was already defeated and that dropping the bomb was completely unnecessary, and secondly because I thought that our country should avoid shocking world opinion by the use of a weapon whose employment, was I thought, no longer mandatory as a measure to save American lives.

MacArthur wrote in tabulations to a US Senate Committee:
Use of the atomic devices was completely unnecessary from a military point of view. We at that point had no intention to invade Japan, the threat of Russia entering the war with Japan on August 11 would have seen them accept the terms of Potsdam by well before September 1 and certainly Operation Starvation would have seen total surrender before October 1.