Well, i hate Nationalism personally, so dont think of me as some Captain America type idiot, but i really dont think the U.S. nuked Japan just to show who's the bigget guy on the block. I mean, that would have been a form of intimidation, and the U.S. probably could have gotten anything it wanted from anyone at that time when we had nukes and everyone else was helpless against them, and yet we didn't try to take over the world, and were in fact pretty lenient on our enemies, it was actually the Russians that gave people a hard time, they were really pissed at those Germans. Anyway, if we had opted to spare the Japanese nukes and invade them on a ground level, well that would've been even worse. We had already gone through Guada Canal, easily one of teh hairiest combat sites in teh entire war, tons of our guys had died in all over the world, the American public was very tired of it. While Japan was largely defeated, a ground invasion would have just been a war of attrition, we would have inevitably won, but millions on both sides would have died, especially considering the unbreakable spirit of the Japanese, they would've given their lives in ocmbat against any odds to stop the AMericans, dropping the nukes, while it was a horrible act, killed far less people than if we had launched a ground invasion, so i really dont think it was a "wrong" thing to do, i mean, it was a WAR, not a tea party.
As for the AI, i have never had to use nukes, or had them used on me, since i almost always win the UN vote or space race before the AI has nukes. Im gonna go up to a higher difficulty and see if the AI starts kicking my ass again
