And now to someone who's long raised questions about the preemptive war doctrine.

NPR: Dangers of Pre-Emptive War Doctrine

What is your position on the whole concept of preemptive war?

NPR: Transcript of Presidential Debate

And unfortunately, I and others who warned at the time, who said, let the inspectors finish their work, you know, do not wage a preemptive war, use diplomacy, were just talking to a brick wall.

CNN: Transcript of Thursday's Democratic presidential debate

For example, if a preemptive attack on the German war machine had succeeded in preventing World War II, we would never know the enormity of the evil it prevented.

NPR: Rules Should Govern Torture, Dershowitz Says