Fu-go has a place, much like the Rape of Nanking, in pointing out a complete willingness via direct example. The Axis committed all the war crimes first, with the possible exception of Finland (and they were mostly in the Axis due to an "enemy of my enemy" situation). I'm not trying to excuse anything here. Nukes are terrible. Attacks on civilians are unforgivable and quite directly Evil with a capital E.

Everything else said and done, it was the US's best option, and a trade most people in the same situation would have made. They didn't kill millions like you said, according to the largest estimates the Japanese themselves made it was at most 226,000 people.

Until the nukes dropped the Japanese were calling for "The Glorious Death of One Hundred Million" campaign. Saying that it was glorious to die for Hirohito, and every Japanese man, woman, and child should die fighting the Allies. The predictions on BOTH sides were millions of casualties. Imagine rather than Hiroo Onoda fighting on for thirty years it was every Japanese person who could.

Then they drop the nukes. A hideous thing. And it prevented something even worse.

Still a war crime. Still terrible. Fuck nukes.