> "It is hard to overstate how many civilians suffered and died in war crimes perpetrated by Japan before and during the war"
I'll take a stab at it.
If one sums together the estimated deaths in Asia caused by Japan (https://en.wikipedia.org/wiki/World_War_II_casualties), both military and civilian, one gets totals in excess of 15-22 million. This compares to about 5 million dead in the Holocaust. So basically, Japan effectively committed 3 to 4 Holocausts, a fact not often remarked upon in these discussions. If we compare that to the roughly 0.25 million estimated dead from Hiroshima and Nagasaki combined, the US would have had to drop 40 more atomic bombs to catch up to the Germans and another 120-176 atomic bombs to catch up to the Japanese. (If one likes, they can subtract out military casualties or otherwise adjust the numbers but the ratios are still high.)
One should also factor in that the Nazis simply executed the majority of the victims of the Holocaust as efficiently as they could in concentration camps. The deaths inflicted during the IJA occupation, on the other hand was accompanied by rape and by torture, including on children, across significant parts of a continent. It's notable that even a diehard Nazi who was in China was so revolted by what he was witnessing that he intervened to protect civilians from the IJA: https://en.wikipedia.org/wiki/John_Rabe. Given the option, it doesn't seem unlikely that many of the IJA's victims would have preferred a death by nuclear blast; at least it would have been impersonal.
So, were Hiroshima and Nagasaki war crimes? I think it's not unreasonable to say that even if they were, they were negligible in the grand scheme of things.
I don't subscribe to the moral calculus that has war crimes cancel each other. When one starts justifying a war crime against civilians because the enemy committed war crimes themselves, one is on very shaky ground.
For example, rape and murder against German civilians is not morally justifiable just because the Nazis were horrendous monsters.
I'll take a stab at it.
If one sums together the estimated deaths in Asia caused by Japan (https://en.wikipedia.org/wiki/World_War_II_casualties), both military and civilian, one gets totals in excess of 15-22 million. This compares to about 5 million dead in the Holocaust. So basically, Japan effectively committed 3 to 4 Holocausts, a fact not often remarked upon in these discussions. If we compare that to the roughly 0.25 million estimated dead from Hiroshima and Nagasaki combined, the US would have had to drop 40 more atomic bombs to catch up to the Germans and another 120-176 atomic bombs to catch up to the Japanese. (If one likes, they can subtract out military casualties or otherwise adjust the numbers but the ratios are still high.)
One should also factor in that the Nazis simply executed the majority of the victims of the Holocaust as efficiently as they could in concentration camps. The deaths inflicted during the IJA occupation, on the other hand was accompanied by rape and by torture, including on children, across significant parts of a continent. It's notable that even a diehard Nazi who was in China was so revolted by what he was witnessing that he intervened to protect civilians from the IJA: https://en.wikipedia.org/wiki/John_Rabe. Given the option, it doesn't seem unlikely that many of the IJA's victims would have preferred a death by nuclear blast; at least it would have been impersonal.
So, were Hiroshima and Nagasaki war crimes? I think it's not unreasonable to say that even if they were, they were negligible in the grand scheme of things.