"Proportionality should be a guideline in war. Killing 50% to 90% of the people of 67 Japanese cities and then bombing them with two nuclear bombs is not proportional, in the minds of some people, to the objectives we were trying to achieve. I don't fault Truman for dropping the nuclear bomb. The U.S.—Japanese War was one of the most brutal wars in all of human history ? kamikaze pilots, suicide, unbelievable. What one can criticize is that the human race prior to that time ? and today ? has not really grappled with what are, I'll call it, "the rules of war." Was there a rule then that said you shouldn't bomb, shouldn't kill, shouldn't burn to death 100,000 civilians in one night? LeMay said, "If we'd lost the war, we'd all have been prosecuted as war criminals." And I think he's right. He, and I'd say I, were behaving as war criminals. LeMay recognized that what he was doing would be thought immoral if his side had lost. But what makes it immoral if you lose and not immoral if you win?"
January 1, 1970
https://en.wikiquote.org/wiki/Bombs