From what I could tell in my recent visit, security progress in Iraq, to the degree there is any, is due to a single development: Sunni tribals taking arms against Al Qaeda, with our help.

To me, this is only indirectly related to the surge. That is, we could have armed the tribals at any point in time, and some commentators, notably Patrick Lang, have long suggested working with the tribes. The surge of American troops may have had some impact on waverers, but even this is doubtful.

It seems to me that the focus on having the Sunni tribals get rid of AQ suggests we could operate with fewer, not more, troops. The tribal fighters become our proxies, the Afghan model.

To the degree more troops are needed, the core function that couldn't be performed by Iraqi elements is the destruction of Shia militias. We haven't really begun this yet, and my supposition is that we may never take this mission - the Shia militias are, in effect, the security forces of the government.

I'd suggest we watch closely to see if there is any movement to engage the Mahdi Army directly. To date, I believe we have been happy with what is in effect an armed truce.

If these extra troops are deployed to target Sunni militias, then eventually this imbalance will simply exacerbate the political problems ("reconciliation") in Iraq.