It’s March. That’s when we have to remove a significant number of troops. From Krugman today:

“In September the Congressional Budget Office analyzed how many U.S. soldiers could be kept in Iraq without extending tours beyond one year. The conclusion was that force levels would have to start dropping rapidly about five months from now, and that the forces in Iraq and Kuwait would eventually have to shrink by almost two-thirds. As the report explains, the Pentagon can use various expedients to maintain a larger force in Iraq, but all of these expedients would threaten to undermine our military readiness.”

We know it, and the Iraqi opposition and al-Queda know it, too. So in April and May the shit hits the fan.