U.S. and Iraqi forces have moved aggressively in the last week to combat Sunni Arab insurgents in neighborhoods across the capital and to establish a stronger presence in religiously mixed districts long plagued by sectarian violence.

But as the new security crackdown enters a second week, they face their most sensitive challenge: whether, when and how to move into the Shiite-dominated slum of Sadr City, stronghold of the Al Mahdi militia....

Any new move into Sadr City remains controversial among military experts. Army Gen. Jack Keane, a former vice chief of staff, and military analyst Frederick Kagan, who were among the most influential advocates of the current Bush administration plan to increase the number of U.S. troops in Iraq by 21,500, have warned that a push into Sadr City would unnecessarily unite the country's now-splintered Shiite leadership.

"Attempting to clear Sadr City would almost certainly force the [Al Mahdi militia] into [a direct] confrontation with American troops," they wrote in a January report for the American Enterprise Institute, a Washington think tank.

"It would also do enormous damage to [Maliki's] political base and would probably lead to the collapse of the Iraqi government."

But now at least one of the authors questions that view. In an interview Tuesday, Kagan adjusted his position and said some early signs of success, including Sadr's recent disappearance from public view and successful sweeps of other heavily Shiite neighborhoods nearby, suggest that U.S. forces could move into Sadr City earlier than Keane and Kagan had advocated.

"It appears that I overestimated the Sadrists and underestimated Maliki," Kagan said. "Our troops have operated in these neighborhoods and these neighborhoods are not resisting."...

Comment by Juan Cole at his blog, Informed Comment

The US is considering attempting to go into Sadr City after the Mahdi Army and Frederick Kagan of the American Enterprise Institute is now in favor. He says he over-estimated the Mahdi Army and under-estimated Prime Minister Nuri al-Maliki earlier. Kagan doesn't have the slightest idea what he is talking about when it comes to Iraq, and he is advising Bush what to do, who knows even less. Sadr City is quiet because the Mahdi Army made a policy decision to cooperate with the security plan, and al-Maliki is in on this deal. The Mahdi Army is the street gangs of the Sadr Movement, to which millions of Iraqis have given their allegiance. You can't uproot a social movement with a few patrols and firefights. Sadrism will be there long after the US is forced to withdraw from Iraq.