U.S. Appears to Take Lead in Fighting in Baghdad

In Basra, three rival Shiite groups have been trying to position themselves, sometimes through force of arms, to dominate recently approved provincial elections.

The U.S. officials, who were not authorized to speak on the record, said that they believe Iran has provided assistance in the past to all three groups: the Mahdi Army; the Badr Organization of the Islamic Supreme Council of Iraq, Iraq's largest Shiite party; and forces loyal to the Fadhila Party, which holds the Basra governor's seat. But the officials see the current conflict as a purely internal Iraqi dispute.

Some officials have concluded that Maliki himself is firing "the first salvo in upcoming elections," the administration official said.

"His dog in that fight is that he is basically allied with the Badr Corps" against forces loyal to Sadr, the official said. "It's not a pretty picture."

Elements of Sadr's militia have fought fiercely, including rocketing the Green Zone, the huge fortified compound in Baghdad where the U.S. Embassy, Iraqi government offices and international agencies are located.

Starting about 5:25 p.m., the Post reporter heard the launch of 14 rockets, which Mahdi Army officers in the area said were aimed at the Green Zone. U.S. officials reported that 12 rounds hit the zone in that time frame, including six that fell inside the embassy compound. An American civilian contractor was killed in a residential area of the embassy compound, and another death was reported in the zone's U.N. compound.

Further volleys landed Friday, striking the office of Iraqi Vice President Tariq al-Hashemi. A guard was killed. Hashemi was not in his office at the time. U.S. officials in the Green Zone have been advised to stay indoors and wear body armor when they venture out.

Several Mahdi Army commanders said they had been fighting U.S. forces for the past three days in Sadr City, engaging Humvees as well as the Strykers. By their account, an Iraqi special forces unit had entered Sadr City from another direction, backed by Americans, but otherwise the fighting had not been with Iraqis.

"If there were no Americans, there would be no fighting," said Abu Mustafa al-Thahabi, 38, a senior Mahdi Army member.

In August, Sadr ordered his militia to observe a cease-fire, a move widely credited with helping to reduce violence across Iraq. In recent days, Sadr officials have said the cease-fire remains in force. But in practice, his fighters and Iraqi and U.S. forces are waging full-scale war in places. Further fighting with his men could slow U.S. troop withdrawals from Iraq.

American commanders said in recent days that their units were taking only a backup role in the offensive and that Iraqi forces were growing strong enough to shoulder the country's security needs.

Maj. Mark Cheadle, a U.S. military spokesman in Baghdad, said he could not make an accurate assessment of what the Post reporter saw without knowing the precise location. He underlined that U.S. troops were playing a backup role in the offensive but that on a battlefield that is "360 degrees," it might seem at times that they were out front. If an Iraqi unit was about to be overwhelmed by an enemy, "of course we are going to assist."