Required, no, authorized, yes.2) Nothing in US law required an invasion, but again not the point. The point is we broke our agreement. You're free to agree that we broke the agreement, but that you think our word means little to nothing.
You don't have to "buy it". The people in charge did. Guess you should have been running the show.3) I don't buy that. Certianly not an imminent threat. Even Bush, as I said, concedes there was no imminent threat and never said there was. So, no, there was never argued there was an inminent threat.
We broke our agreement? Even if so, that doesn't make anything illegal. Technically, if you break a treaty agreement, then it no longer applies anyway.4) Again, the dispute here is that we broke our agreement. You seem ready to concede that we did.