“The crisis gave an opening to a handful of senior officers and military policy analysts in Washington to push for an American-heavy strategy of putting troops in Iraqi neighborhoods around the clock - which had not been done on a large scale - while isolating and attacking the main catalysts of the sectarian violence.
General Petraeus, with other commanders, like then-Col. H. R. McMaster, had for years been pushing the Army to change its focus from killing the enemy to helping ordinary Iraqis cope with insurgents - the essence of modern counterinsurgency strategy.
As fresh troops arrived, the generals began deploying them across Baghdad, mostly in small outposts called joint security stations. The stations were seen as the key to securing the capital; for the first time, Americans could credibly promise that they would protect Iraqi civilians from the insurgents. The extra troops also allowed American commanders to initiate a series of offensives last year against the strongholds of Al Qaeda of Mesopotamia and other Sunni extremist groups in and outside of Baghdad and then, in 2008, against the Mahdi Army, the Shiite militia.”
Peter Wehner has some additional commentary on the piece.