Baghdad, Iraq ? Sunni insurgents, resilient despite the five-week security crackdown in the capital, killed at least six more U.S. troops over the weekend. A Sunni car bomber hit a largely Shiite district in the capital Sunday, killing at least eight people.

The American military said four U.S. soldiers died and one was wounded when the unit was struck by a roadside bomb in western Baghdad. During the ongoing security sweep in the capital and surrounding regions, the battalion had found eight weapons caches and two roadside bombs and helped rescue a kidnap victim, the military said.

A fifth soldier was killed in an explosion in Diyala, an increasingly volatile province just northeast of the capital. A Marine died in fighting the same day in Anbar province, the vast, largely desert region that sprawls west of Baghdad to the Saudi Arabian, Jordanian and Syrian borders.

All of the U.S. victims were killed on Saturday, the military said in a series of statements that also reported that a seventh soldier died from noncombat injuries but gave no other details.

Soldiers of 5th Battalion, 20th Infantry Regiment, 3rd Stryker Brigade Combat Team, out of Fort Lewis, Wash., pull security while on patrol Thursday in Baqouba, Iraq. The regiment was moved to Diyala province to reinforce the 3rd Brigade Combat Team, 1st Cavalry Division, to try to quell ongoing violence in the area.

While U.S. and Iraqi troops have flooded the Baghdad streets and a heavily armored American column was sent north to adjacent Diyala province, attacks on American and Iraqi forces have been robust.

Defense Secretary Robert Gates said the success of the mission, which was starting well, could not be measured for months and that it was designed to give the Iraqis more time to settle political and sectarian differences.

“The issue that we’re all trying to figure out is how best do you get the Iraqis to reconcile their differences – because after all, this is not going to be solved by the military. It has to involve political reconciliation in Iraq, among Iraqis,” Gates said on CBS’s “Face the Nation.”

“We’re basically buying them time,” he said.

The latest deaths raised the American military death toll in Iraq to 3,217 since the war began in March 2003, according to an Associated Press count.

In Shiite-controlled eastern Baghdad, a U.S. Bradley fighting vehicle was hit by a roadside bomb Saturday evening, set afire and destroyed, said spokesman Maj. Steven F. Lamb said. There were no casualties.

Across Iraq, at least 20 people died Sunday, a sign that violence continued to abate as U.S. and Iraqi forces press ahead with what many view as a last-chance bid to quell the sectarian violence in Baghdad and central regions of the country.

At least 12 of those killed died in Baghdad and eight of them were slain in the car bombing in a predominantly Shiite district, police said. The attack targeted people grilling meat along the street, to offer as charity on a Shiite Muslim holiday marking the death of the Prophet Muhammad. Police said 28 people were wounded.

Police said the bodies of 16 people, most shot in the head and showing signs of torture, were found dumped nationwide, just five of them in Baghdad.

A U.S. official, meanwhile, blamed al-Qaida in Iraq for chlorine bomb attacks that struck villagers in Anbar province earlier this week but said tight Iraqi security measures prevented a higher number of casualties.

Three suicide bombers driving trucks rigged with tanks of toxic chlorine gas struck targets in the insurgent stronghold including the office of a Sunni tribal leader opposed to al-Qaida. The attacks killed at least two people and sickened 350 Iraqi civilians and six U.S. troops, the U.S. military said Saturday.