Hard to tell. We keep hearing about the need to suppress Muqtada al-Sadr's (Shi'a) Mahdi Army. But the opening round in the Battle of the Surge was directed at Sunnis.
Robert Dreyfuss describes it at his blog in Slaughter on Haifa Street 01/10/07:
Set aside the sheer irony that the United States is fighting with heavy weapons, helicopters and F-15s less than a mile from the Green Zone in Baghdad. What happened this week in the Haifa Street area of Baghdad is this: the sectarian, Shiite-run puppet government of Iraq enlisted the United States in an escalation of its own bloody ethnic cleansing of west Baghdad.
The full force of U.S. military power was brought to bear on a Sunni civilian neighborhood in the center of the city. Dozens were killled. ...
... it appears utterly clear that the Bush "surge" in Iraq will be aimed at purging Baghdad of the Sunni insurgency, leaving the Shiite fundamentalists intact and in control.
Juan Cole reminds in this 01/10/07 post at Informed Comment us that we've won several times before in that same area:
Haifa Street has been an important thread in the saga of Iraq's civil war. [In] July of 2004 we saw the huge "Operation Haifa Street," involving 3000 US troops. There was the massive carbombing there of a police station in 2004, which doesn't seem to show that "Operation Haifa Street" was exactly a success. Even at that time, the US GIs called it "Grenade Alley" and "Purple Heart Boulevard" and fought constantly with locally based guerilla groups. It has been radicalized and supposedly pacified over and over again. By March 2005, the NYT found that the tide was turning on Haifa Street. CSM reported that it had calmed down under Iraqi army supervision by May of 2005. A year and a half later, and it is still a "terrorist stronghold" and we have yet another pacification effort. Or maybe by now it is just being levelled by airstrikes. Or maybe we really have been duped into ethnically cleansing it on behalf of the Mahdi Army. Bush's Iraq War is like Groundhog Day, the Bill Murray science fiction film about the guy doomed to live the same day over and over again. How is 2007 different on Haifa Street from 2004?