Obama won the Nobel Peace Prize for Repudiating the Bush/Cheney Doctrine

Preemptive war has always been regarded as OK: if you see an enemy massing its troops at the border, entering the launch codes on its missiles, and so forth, you do not have to wait until that enemy actually strikes. Preventive war, by contrast, has not generally been regarded as OK. Nonetheless, it's one of the pillars of the "Bush Doctrine":

I should say, at the outset, that I have not read every interview Obama has given, and so there may be statements that are clearer than the ones I've found. That said, the clearest one I know of is from The Audacity of Hope (pp. 308-9). Having said that the United States has the unilateral right to defend itself against an actual attack, he writes:


"I would also argue that we have the right to take unilateral military action to eliminate an imminent threat to our security -- so long as an imminent threat is understood to be a nation, group, or individual that is actively preparing to strike U.S. targets (or allies with which the United States has mutual defense agreements), and has or will have the means to do so in the immediate future. Al Qaeda qualifies under this standard, and we can and should carry out strikes against them wherever we can. Iraq under Saddam Hussein did not meet this standard, which is why our invasion was such a strategic blunder." (Emphasis in text.)

As far as I can tell, this is a way of saying: I support preemptive war but not preventive war, without using those terms (which are technical and unnecessary in this context.) Obama supports a right to anticipatory self-defense that is restricted to imminent threats by an enemy who is actively preparing to strike, and either has the capacity to do so or will have it in the immediate future. It therefore does not include more speculative threats, like Iraq before the war.

Obama On Preventive War

The Nobel Committee said, in part:

Obama has as President created a new climate in international politics. Multilateral diplomacy has regained a central position, with emphasis on the role that the United Nations and other international institutions can play. Dialogue and negotiations are preferred as instruments for resolving even the most difficult international conflicts. The vision of a world free from nuclear arms has powerfully stimulated disarmament and arms control negotiations. Thanks to Obama's initiative, the United States is now playing a more constructive role in meeting the great climatic challenges the world is confronting. Democracy and human rights are to be strengthened.

Nobel Committee Announcement