The Zero Option

Yes. What Kevin said. I think some of these residual force ideas about Iraq make a little bit of sense in a vacuum, but when you think about how things play in the real world, I think it's obvious that to secure the benefits of withdrawal from Iraq the United States needs to withdraw from Iraq in a really complete way. If there's a need to blow up some al-Qaeda installation in Anbar Province (frankly, I doubt that'll be the case, but this seems to be the main practical worry) that can be done by people who are stationed outside of Iraq and who leave Iraq really, really quickly once the blowing up is done.