US troops do absolutely nothing on Korea and Europe other than as stand-by and a geopolitical deterrent. The troops in Iraq were acting as the fighting force for the official regime. These are very VERY different things. US toops were occupying Iraq, they are not occupying South Korea.

That's more or less my point, isn't it? It would have been possible to (attempt to) hand over responsibility to the Iraqi military while still keeping troops there in case things went south (as they did).

This NYT article has some very interesting background:

http://www.nytimes.com/2011/10/22/world/middleeast/united-st...

After reading the article and learning some of the intricacies I really don't feel ready to blame anyone in particular. It seems to be a "system outcome" of the interactions and the (local) conditions.

Let's not forget a lot of Irakis wanted the US to leave, fully and completely:

> Possibilities being discussed are for some troops to return in 2012, an option preferred by some Iraqi politicians who want to claim credit for ending what many here still call an occupation,...

That "some" is about the politicians, the mood in the streets wasn't just "some" people who wanted all foreign soldiers to leave, if I remember anything from the news we heard at that time.

Given the state of the Iraqi military, things would have gone south immediately, and the troops would never leave.

Would they, though? I think it is a plausible argument that things would have been less likely to go south if the opposing force knew the U.S. forces were there to step in if necessary. While things might still have ended badly, I think there's no question that pulling the U.S. troops out so soon made the collapse a certainty.

At the very least, ISIS would not have been armed to the same extent by fleeing Iraqi security forces.