I get it, we all have our own opinions on the A bomb and this thread is about Iran/Israel/Hamas but after reading Eisenhower's memoir "the white house years" for a senior leadership class I went down a rabbit hole and an overwhelming number of senior leaders believed the war with Japan was already come to terms with surrender
"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"
The Japanese had, in fact, already sued for peace. The atomic bomb played no decisive part, from a purely military point of view, in the defeat of Japan.
— Fleet Admiral Chester W. Nimitz, Commander in Chief of the U.S. Pacific Fleet,
The use of [the atomic bombs] at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender because of the effective sea blockade and the successful bombing with conventional weapons ... The lethal possibilities of atomic warfare in the future are frightening. My own feeling was that in being the first to use it, we had adopted an ethical standard common to the barbarians of the Dark Ages. I was not taught to make war in that fashion, and wars cannot be won by destroying women and children.
— Fleet Admiral William D. Leahy, Chief of Staff to President Truman, 1950,
General MacArthur was also against it, to me these were the people on the front lines who could best gauge where the war was actually going vice those that were coming up with worst case scenarios