As for the actual “withdrawal” of U.S. troops from cities, officially effective today, Lindholm calls it largely symbolic:
I don’t have a whole lot to say about the milestone, in terms of predictions. The questions regarding Iraq’s future remain both political and unanswered. If political identity congeals around some functioning incarnation of a state, democratic or otherwise, there will be stability. If, on the other hand, political identity congeals around the incoherent violence that continues even now, then the sporadic attacks will take shape as a coherent movement, signaling a return to ethno-sectarian war.
If that happens, though, I wonder if it will be so easy for U.S. forces to re-interpose themselves between the Iraqi belligerents. If the reason behind the past two years’ worth of improved security is that Iraqis were simply postponing their final showdown until U.S. forces left, then the logic behind silencing the guns was based on a one-way trajectory of American involvement. Should it become clear that U.S. forces will continue to re-enter the fray to uphold a status quo that is unacceptable to one party or another, then silencing the guns again means losing without a fight.
At that point, it’s hard to see how attacks on U.S. forces won’t again become the primary priority of the insurgency, as opposed to the attacks on civilians we’re seeing today. And if that happens, it will fundamentally change the dynamics of the Iraq War, both tactically on the ground, and politically in public opinion.