Suppose Germany had developed two bombs before we had any bombs. And suppose Germany had dropped one bomb, say, on Rochester and the other on Buffalo, and then having run out of bombs she would have lost the war. Can anyone doubt that we would then have defined the dropping of atomic bombs on cities as a war crime, and that we would have sentenced the Germans who were guilty of this crime to death at Nuremberg and hanged them?
But, again, don't misunderstand me. The only conclusion we can draw is that governments acting in a crisis are guided by questions of expediency, and moral considerations are given very little weight, and that America is no different from any other nation in this respect.

"President Truman Did Not Understand" in U.S. News & World Report (15 August 1960)