Leaving Iraq

I think I am missing some important piece of logic for the "out-of-Iraq" movement. I realize I'm an outside and far from the reality of the situation, but I can't see how withdrawing the troops right now (or soon) with have a stabilizing effect. Currently as I understand it, it is might that is in control and since the insugence is well armed they will become the dominant power if the US leaves. With three different factions separated by centuries of conflict I fail to see how the pull out won't result in further destabilization. All I can imagine is a civil war with in Turkey is pulled in since the Kurds may take this as an opportunity to try and get a Kurdish nation. Couple that with a what is going on in Iran and how the Shiites is influenced by Iran and I can't see the rational. The ensuing chaos would be worse that the Israeli conflict and people would clearly (and rightfully) blame the US.

From what I understand about the motivation of many of the western world attackers, they are tired of the foreign policy that hurts their people. If this is true at all and I'm not completely wrong about the effects of the pull out, wouldn't it be the worst move?