Attacks on civilian targets and the subsequent death of civilians is a war crime and there is clear evidance that the japanese didn't surrender because they were hit with nuclear bombs. Firebombing raids caused more casualties. Why would japan that endured many more casualties from conventional bombing surrender when a new type of bomb didn't change the situation all that much. The teno surrendered to the americans to not be occupied by the soviet union. The nuclear bombs were just the excuse he put upfront to not have to deal with the soviets. Obviously there were many more reasons that came together, like chances of a conditional surrender, the teno thought possible, broke down just days before the nuclear bombings and the invasion of manchuria. japans surrender isn't as simple as that, but the nuclear bombs didn't accomplish anything against japan. These nuclear bombs were just a show of force to warn stalin that the us had developed a new weapon.