If, then yes. But that's the big question, if. How would you know until after the fact that it would do anything? And which war is it? War in afghanistan it might end, such as it is. But war on terror? That won't be ending so long as people are free to disagree with each other. Well the terror part won't, we might decide to stop treating it as a war. Then again, if bin laden was in a position to be killed, why aren't the us soldier types doing the killing (or taking prisoner)? But back to the question you asked: If I knew, without question, that killing one person would end the war, then yes, I'd kill them. Not that that'll ever happen, is a nice idea on paper, but in practice I don't see it making much difference.