U.S. troops and helicopter gunships continued to harass the Shiite Muslim militia force controlling the shrine of Imam Ali on Sunday, as Iraqi officials again warned that erratic progress in the latest attempt to peacefully resolve the standoff left the militia with only a few hours to meet government conditions.

Qasim Dawood, the minister of state, told reporters that interim government officials are pursuing political and military options to eliminate the Mahdi Army of rebellious Shiite cleric Moqtada Sadr. But, repeating a warning delivered intermittently for more than a week, he said Sadr's refusal to meet with negotiators or provide a clear, written statement of intent would force the government to ask U.S. forces to mount a major operation against the militia.

"We are probably working in both ways, the peaceful solution -- I don't like to call it a political solution, I will call it a peaceful solution -- or a military solution," Dawood said.

Meanwhile, a kidnapped American journalist was released after the intercession of a Sadr aide. Micah Garen was taken captive more than a week ago in the southern city of Nasiriyah by a group that demanded the withdrawal of U.S. forces from Najaf.

"I am very grateful to everyone who worked to protect me and guarantee my release and I thank my friends in Nasiriyah and my family and fiancee who spent three months with me in Nasiriyah," Garen told al-Jazeera, the Arabic-language satellite television network, by telephone, speaking from the office of Sadr's organization in Nasiriyah.

The day brought official reports of five U.S. military deaths, none connected to the fighting in Najaf. In Anbar province, which extends west from Baghdad to the Syrian and Jordanian borders, three Marines were killed at unspecified locations and a fourth died in Fallujah when his Humvee hit an M1-A1 Abrams tank, the military said. In the northern city of Mosul, a soldier was killed by a roadside bomb.

In Najaf, an aide to Sadr said the wall of the shrine compound was damaged by U.S. fire Sunday night, according to the Reuters news agency; the claim could not be independently confirmed. Apache helicopters and a fixed-wing AC-130 Spectre gunship were striking targets in the cemetery north of the city, where fighting has occurred daily since Aug. 5.

U.S. commanders and Iraqi officials said the steady pressure from American guns and patrols has weakened the militia, which aims to drive foreign forces out of the country and supports Sadr's call for a theocracy similar to that in neighboring Iran.

A fighter who gave his name as Haider Hussein and his age as 17, asked dismissively: "Are there any negotiations going on?" Clad in a white track suit with a red stripe and holding a sniper rifle, Hussein stood with other militiamen, some of whom said morale was high. They said they believed in Sadr and in some religious leaders who have urged them to fight on.

Dawood, the government minister, claimed that more than 300 fighters were captured on Friday, when Sadr cleared weapons out of the shrine and offered to transfer custody of it to Grand Ayatollah Ali Sistani, Iraq's senior Shiite cleric.

Aides to Sistani, who is in London for medical treatment, said they have refused to accept the keys to the shrine until its treasures can be inventoried. The aides and Dawood said this was the sticking point in negotiations. They said no inventory would be possible until the shrine was no longer dangerous -- in effect, until the Mahdi Army had left the area.

A government delegation met with Sistani on Sunday, but a delegation statement said members had only inquired about his health.

Late Sunday, Iraqi police cars could be seen driving through the streets of Najaf, their loudspeakers proclaiming that the Mahdi Army's commanders had fled the city and calling on "all the people of Najaf to go back to the old city," in the words of one officer.

There was no clear evidence to support the claim, and the old city appeared to remain far too dangerous for people to begin returning to their homes. "This is the proof of the failure of the Iraqi police," said a spokesman for Sadr, Ahmed Shaibani.

Lt. Cmdr. Paul Shaughnessy, a Marine chaplain, conducts mass at camp Hotel in Najaf. An Iraqi civilian carries a child through a neighborhood in Najaf where members of the Shiite militia known as the Mahdi Army have clashed with U.S. and Iraqi forces.