How Vital is Iraq?

What to think about the possibility of Iraq demanding that a troop withdrawal timetable be attached to the Status of Forces Agreement currently being negotiated? Kevin Drum has the relevant links and caveats here. I’d simply add that an Iraqi request for a withdrawal timetable presents a useful thought experiment: By removing the moral obligation to prevent the country from descending even further into a bloody civil war, it forces advocates for a continued engagement to do some soul-searching. If an unstable Iraq is as serious a threat to American national security as they maintain, then the logical conclusion is that we should maintain our troop levels despite the request to leave. Obviously, we’re a long way off from facing that choice. But I’m curious to hear from anyone who has unequivocally argued for a continued troop presence until Iraq is a stable, functioning sovereign state, whether and how this might change your thinking.