No matter how bad a situation is, it can always get worse.
That principle has made me skeptical of the argument that rapid U.S. withdrawal from Iraq couldn’t possibly precipitate a civil war, because a civil war is already in progress. There’s a continuum between sporadic inter-ethnic violence and full-scale civil war, and the removal of the U.S. as buffer might easily move the conflict toward the full-scale war end of the spectrum. And Zalmay Khalilzad is no Paul Bremer: he appears to know what he’s doing.
However, the worse things get under current policy, the stronger the argument for trying something else. I’m sure the warbloggers will figure out some way to interpret this weekend’s tit-for-tat massacres in Baghdad (the bombing of a Shi’a mosque on Saturday, random killings in by Shi’a militiamen in a Sunni neighborhood on Sunday, then the bombing of a second Shi’a mosque) as good news, or alternatively to deny their reality, but to my eyes they look pretty disastrous.
That doesn’t mean that withdrawal is the right thing to do. It does, however, put the onus on the defenders of the “more of the same” strategy to explain why we should expect maintaining the same policies to lead to different results.