Simple answer is, that although I don't agree with all Blair and Bush's policies, they are attemting to find world peace, NOT world domination as you suggest. By your definition Mark, Adolph Hitler was quite justified in his 'final solution'. In fact, we sat back on that one, because we knew about the extermination camps LONG before we did anything about it.
Harold Shipman killed purely for pleasure. (probably in excess of 200). He had to feel he was in some sort of control. At least he did the decent thing in dying !
Pleased this hasn't turned into a 'slanging match', because although I don't share in your beliefs, Mark, I will defend your right to freedom of speech until my dying day. Something incidently, that never existed under Saddam !