Basra Raid Finds Prisoners With Signs of Torture

The operation lasted several hours and primarily targeted an area near a busy market, according to residents interviewed in Sadr City. By afternoon, there were no signs of U.S. or Iraqi soldiers in the densely crowded streets lined with posters of Sadr and banners lauding the Mahdi Army.

U.S. military officials said they would continue the security sweeps to facilitate a plan to house U.S. and Iraqi troops in a police station on the edge of Sadr City, where as many as 2 million people live. The new military post, similar to those being constructed in other neighborhoods, is a key component of Maliki's security plan to build public trust in Iraq's security forces and ensure that areas are not retaken by insurgents.

"It is a multi-day operation, continuing operation," said Lt. Col. Christopher C. Garver, a U.S. military spokesman.

In Sadr City, black-clad militiamen have vanished from the streets. Senior Sadr officials and Mahdi Army leaders have fled to Shiite cities in southern Iraq or to neighboring Iran. Some fighters said in interviews that they wanted to engage the U.S. troops but were under strict orders from Sadr to maintain a low profile.

"We feel upset, but what can we do?" said Laith Abu Bakr, 34, a Mahdi Army fighter. "We have orders not to act."

Sadr's motive for allowing the security operation in his stronghold was unclear. Some Shiite politicians have suggested he wants to boost his political credentials and improve his image, but others say he hopes to rid his movement of rogue elements and rivals.

Publicly, however, he has started to criticize the U.S. involvement in what he said should be an Iraqi operation. Sadr has long opposed the U.S. occupation and has issued strong calls for a troop withdrawal. In 2004, the Mahdi Army staged an uprising in Shiite areas, prompting U.S. forces to storm Sadr City.

On Sunday, Rahim al-Daraji, the mayor of Sadr City, said "as long as there is an Iraqi leadership, they are most welcome. The Americans can go into Sadr City."

"The people were very cooperative and were very happy because these forces are coming to protect them," he said.

But some residents said they felt safe under militia protection and questioned the presence of U.S. troops.

The Mahdi Army is "treating us very well," said Riyad Hamid Swadi, 40, the owner of a small junk shop. "What are the Americans doing here?"

A senior Sadr official said he did not believe that Sadr had agreed to allow U.S. troops to be stationed inside Sadr City and warned that their presence could provoke the Mahdi Army.

"This will create a spark," Sheik Ayad al-Khabi said. "They are going to drag the Shiites into a fight."

Separately, Maliki announced plans to reshuffle his cabinet in the next two weeks, a move he has promised for months. Maliki's aides have indicated that he intends to replace several Sadr loyalists in charge of key ministries, including the Health Ministry, which has been plagued by allegations of corruption.

Falah Shanshal, of the Sadr bloc in parliament, said that Sadr's supporters had given Maliki a list of replacements for the ministry posts and that they would block attempts to wrest ministries from their control.

Staff writer Ernesto Londoño, special correspondent Saad al-Izzi and other Washington Post staff contributed to this.