BAGHDAD, Iraq -- Shortly before 6 a.m. at Camp Liberty in Baghdad, 1st Sgt. Dave Meyer gave the mission brief to his soldiers: Patrol the streets, but keep a low profile. Don't engage locals. Let Iraqis take the lead.

"Hanging out," said Sgt. Meyer, 36.

Until December, Sgt. Meyer and his fellow soldiers in Charlie Company of the 1st Battalion, 87th Infantry, had patrolled this part of western Baghdad, a heavily Sunni area bordered on the north by the poor Shiite neighborhood of Shula.

At the end of the year, they had turned the territory over to an Iraqi battalion, predominantly Shiite.

But last week, the Americans were pulled out of their beds in the city of Abu Ghraib and sent to their old neighborhood. For five tense days, they patrolled the neighborhood -- part of the effort to tamp down fighting between Sunnis and Shiites that began with the bombing of one of the holiest shrines of Shiite Islam, the Golden Dome in Samarra.

For the American soldiers it was an unfamiliar role. They found themselves in the middle of a fight they could comprehend only partly, stuck between two sides on the edge of civil war.

This was an Iraqi problem, their commanders told them. The solution would have to be Iraqi, as well.

"It's like a secret war," said Lt. Justin Glass, a 27-year-old from Tallahassee, Fla. To his Iraqi translators and the Iraqi soldiers, he said, "It was like the Oklahoma City bombing."

"There's stuff that we may never know. We're sheltered because of cultural barriers."

"It felt -- at times -- like someone else's war," said Capt. Gregory Stone, 28, of 1st squadron, 71st cavalry.

When the mosque bombing happened, Capt. Stone had been at a district council meeting in the Shiite neighborhood of Khadamiya, talking with local leaders about what to do with a repeat check-fraud offender.

One of the Iraqis took a cell-phone call. The translators stopped translating. Baffled U.S. soldiers looked on as a councilman talked to the others with great animation.

"Then," said Capt. Stone, "all hell broke loose."

Before long, Capt. Stone was investigating allegations of reprisals against Sunni mosques. But since neither he, nor any other American, was allowed to enter the houses of worship, they remained on the outside, looking in.

"All we could do was stand outside and take pictures," he said.

"We don't want to get stuck between Sunnis and Shiites, fighting for a mosque," Sgt. Meyer said.

"We were always welcomed in Shula and the Shiite areas," he said. By contrast, in the Sunni neighborhood of Amariya, "They didn't want us."