Laos and Cambodia weren't participants in the war but that doesn't really feel like it matters all that much. Whenever I talk about the bombings of Cambodia and Laos with Americans (who - liberals and conservatives alike feel they must always defend) I sometimes here "well we bombed cities in Germany and Japan in WW2 and no one talks about those being war crimes". But were they? I really don't know much about those bombings. My gut says yes they were also war crimes but we just accept them because they were combatant countries?
I still don't understand this though- why not just set off a bomb near the island first to demonstrate its power? The U.S. had another one it could use if Japan didn't surrender.
America wanted to kill as many Japanese as possible. Like killing them was an active goal and viewed as a positive. America had completely, totally dehumanized all Japanese people. It differed from genocide only in that America never made any effort to kill all Japanese people.
The people who were drawing up the bombing plans didn't think "Well, we want to maximize our effect while minimizing civilian casualties." They literally said "This city hasn't been bombed much, let's kill all the people here". They picked the targets they did because they knew it would maximize the death and suffering of Japanese people.
It's even worse than that. They left the cities unbombed so that they could gauge the destructive power of the weapon on a clean slate. They were literally called tests 2 and 3. Monstrous given the fascists were already on the ropes.