In his press conference yesterday, General James T. Conway, the Marine commandant, repeatedly referred to a U.S. withdrawal from Iraq as deleterious for American credibility. Conway declined to spell out exactly how a loss of credibility would endanger America. Rather than let it go, some alert reporter opted to press the commandant:

Q: General, can I ask you -- what you said earlier, you said, we want to come out with as much credibility as the U.S. had when we went in. Could you elaborate on that? What do you mean by credibility? How is U.S. credibility deterred? And is that something that you can tell the American public is worthy of an exchange of your Marines' lives, to maintain that U.S. credibility?

GEN. CONWAY: I don't think that's a fair question or comparison. I will talk about American credibility and say that we are a superpower nation, I think, that stands for some very positive things in this world at this point in time. I think the world would like to see us continue in that role in places outside of Iraq, and I think it's important that it's understood that we are a good partner, we are a good coalition member, and that we will respond when it's in our nation's vital interest. If there's any doubt about that, I think the world is probably a less safe place.

Concede all of Conway's points. There's no reason to believe that a U.S. withdrawal from Iraq will prompt retrenchment from other places around the globe. Camp Bondsteel will not close up shop if FOB Justice does. Bagram Airbase certainly won't. The U.S. will still be a superpower if it leaves Iraq in one year or ten years. Credibility is a less useful concept here than capability -- what the U.S. will be able to do in the event of a challenge to its power -- and Iraq saps U.S. military capability severely, with little in the way of offsetting benefit. Following Conway's reasoning, that makes the world a more dangerous place. None of this is to say that there won't be consequences to a withdrawal from Iraq, but American superpower status won't be a casualty of the war.