Earlier quoted context omitted.
It was indeed an illegal invasion, but the problem was not having taken over in the Golf War - it should have been settled then.
It was settled then - Saddam's chemical weapons were destroyed in the aftermath of the Gulf War.
That's not settling anything. A leader of a country that tries to commit genocide and/or annex another country isn't fit to rule.
That's what we learned from WW2, remember?