Unrest resurfaces in Sadr City

But a more finely tuned measure of the tensions may be found among the one- and two-story homes and shabby storefronts of Sadr City. As the crisis deepened, the Associated Press toured Sadr City yesterday to observe its rapid swing from relative quiet to a return of the Mahdi Army swagger before the US military troop buildup in Baghdad last year.

Sadr City - named after Moqtada al-Sadr's father, who was assassinated in 1999 - is seen as critical to the overall stability and security of the capital.

A resurgence of Mahdi Army attacks and opposition could roll back the gains that have allowed Baghdad residents to take cautious steps toward normal life and offered Washington hope of accelerating troop withdrawals.

But recent days have resurrected old challenges.

Sadr's militia forces, estimated at about 60,000, now seem itching for a fight. The current crisis came to a head over US and Iraqi raids that have detained hundreds of Mahdi Army loyalists even as the group maintained a shaky cease-fire since August - which the Pentagon has credited for helping bring down violence.

The tensions have spilled over into street battles in Basra between Mahdi fighters and Iraqi government forces. Fighting also has flared in other cities across southern Iraq's Shi'ite heartland - where Iran is hedging its bets by supporting factions of the Mahdi Army and its main Shi'ite rival.

Mahdi fighters also are blamed for a series of rocket barrages on the US-protected Green Zone, which was hit again yesterday. The Pentagon appears to want no part of the current troubles. Commanders worry that American troops could be drawn into difficult urban conflict, sapping energy from the fight against Al Qaeda in Iraq and other Sunni insurgents.

US forces have made only sporadic stabs into Sadr City, choosing instead to strengthen a security cordon on the outskirts. US commanders, meanwhile, have a limited presence in southern Iraq and show no signs of diverting soldiers - as they did in the last major fight against the Mahdi Army in 2004.

"We are a different force than the one you saw in 2004," a senior Mahdi commander said at his Sadr City home.