As you can probably imagine, Ezra and I emailed a lot of Iraq and foreign policy experts for our piece on the significance of the surge. Not all got back to us, and one, Princeton professor and Woodrow Wilson School dean Anne-Marie Slaughter, just got back to me last night. But her comments are really worth printing, as they're a very good distillation of the essential truth here. The various factors in the decline in violence in Iraq - Moqtada al-Sadr's stand-down, the "Anbar Awakening" in Sunni areas, ethnic cleansing, the troop increase - are very difficult to disentangle, and it's foolish to draw conclusions like "the surge worked" or even "troop increases win counterinsurgencies" from such a complicated situation. Here's Slaughter's response, in full:

Identifying a single cause, or even a single primary cause, for the decline in violence in Iraq is symptomatic of what is still wrong with our Iraq policy. Surely we have learned by now that causes and consequences in Iraq are part of a complex tapestry that is woven by government officials in Baghdad, Washington, Tehran, Riyadh, and Damascus, among others, as well as by individual actors from different tribes, religious groups, and political factions across Iraq itself and outside. The increased troop presence helped. So did the Anbar Awakening, the sad reality of ethnic cleansing, and al-Sadr’s change in tactics or perhaps change of heart. But pulling one thread out of this tapestry, highlighting it, and then basing future policy decisions on the assumption that “it made the difference” is folly.

Anne-Marie Slaughter is the Dean of the Woodrow Wilson
School of Public and International Affairs and the Bert G. Kerstetter
'66 University Professor of Politics and International Affairs, Princeton University.

--Dylan Matthews