it's certainly an interesting moral question.

The theory is that dropping the bombs would've brought the quickest end to the war with the least amount of lives lost. Whether that holds true or not is a hard question to answer, from what little research i've done, the japanese empire at the time was in quite the odd position, kamikaze being notable for obvious reasons. (we also did a lot of clean work after the fact IIRC, so it's not like we just left them out to dry)

i've dug a little into the sino-chinese, and tangentially sino-russo war which were earlier escapades of the japanese. They were pretty ruthless to the chinese. Empire conquesting is about as completely as you can describe it. Similar to germany, but without the bad part.

There was of course, pearl harbor, which is probably the worst attack the US has faced outside of war.

another interesting thought is the soviet military tactic of throwing human lives at the problem until it goes away, especially under stalin. the USSR itself actually tried to redefine genocide at some point to exclude your own population. (and of course modern day russia as well)

i don't personally see very much mention of the soviets tactics in regards to just throwing lives at problems, but that's another story. Regardless, the bombings of japan are something to think about in a respectful manner, as many many people died over the course of the bombings.

PS: weird fun fact, the guy that developed the fujita scale (ted fujita, i know, shocking right) was actually supposed to be in the bombing target, however due to weather the location was changed and he ended up surviving the bombings. It's kind of weirdly poetic, that the guy who didn't get bombed by the US due to weather, classified the scale used to determine the severity of tornado damage.