It's hard to understand why the Obama administration would consider leaving only about 3,000 U.S. troops in Iraq after 2011. A force so small would have little ability to contribute to U.S. interests by helping to build a democratic Iraq or by preventing it from sliding back into civil war. But it would incur all the risks and costs of a continuing troop presence.
A few thousand troops would have some residual capacity to provide training and modest logistical support for the Iraqi Security Forces. But that's about it.
They certainly will not be in any position to play the vital peacekeeping role that produced the phenomenal drop in violence starting in early 2007 and that made possible Iraq's hopeful - but entirely incomplete - democratic progress in 2008-2010. The loss of that role could well result in a relapse of Iraq's civil war that might suck in neighboring states and metastasize from civil war to regional war.
A U.S. force so small will have little, if any, intelligence-gathering capacity or situational awareness. It certainly won't be able to support Iraqi development and reconstruction.
Even with regard to training and logistical support (the Iraqis still need both, the latter more than the former), a few thousand U.S. personnel will not be able to provide the same levels of training that U.S. forces have in the past. Both the partnering of U.S. and Iraqi units in the field and the attaching of American advisers to Iraqi formations will have to be cut back.
Perversely, training and logistics are the only two areas where the Iraqis may not even need military help. They could, in fact, go out and hire Western contractors to do the job for them, because in these areas contractors actually are a reasonable substitute for U.S. forces. In short, we could be leaving a force in place that is only capable of performing missions that U.S. troops are not uniquely necessary to perform.
A force of only a few thousand Americans also will have a greatly reduced capacity to undertake unilateral counterterrorism operations. That mission must then be left largely to the Iraqis, who have proven able but not always willing - especially when Iraq's own complicated politics make it inconvenient to hunt down death squads and terrorists.
