The United States seems committed to withdrawing its forces from Iraq by the end of 2011. Experts worry that the relative calm since mid-2007 might not last once US troops depart. Indeed, there are serious questions about whether Iraq can be a viable state in the long run. If Iraq becomes a cockpit of instability, as it was during the first four years following the US invasion, the implications for the region are ominous. Unfortunately, the factors that cause turbulence, including Kurdish secessionist aspirations and simmering Sunni-Shiite tensions, are largely beyond the control of the United States.