Yes, if the Japanese and the Germans had nuclear weapons they most certainly would have used them. So you think the US is not better than the Japanese and Germans during WW2, right? Well, there are countries that have nuclear weapons and are going to use them against US, and the rest of the world is going to say, "well, what can you expect, the US used them first." So there's going to be no defense. Let's see how your explanation of "the unique environment that existed in WW2" plays out when we get a taste of our own genocide.