'In the Land of the Blood Feuds'

"If the Mahdi Army kills the sheik, this will be a big issue," Mahawili said. "The Mowafat will take revenge."

Mahawili has his own concerns. Musayyib's town council is controlled by Sadr loyalists who back the Mahdi Army, he said. The previous week, he had received an official summons to Baghdad. He refused, worried about an ambush.

"Anything can happen," he said. "I can die anytime."

Khidr

Twenty miles to the northwest, in the lush marshlands of Khidr, U.S. forces face an elusive Sunni foe. Al-Qaeda in Iraq recruits local tribesmen here, and vendettas unfold both among and within the tribes.

Sunni groups launch attacks from Khidr against Shiites farther south and east. Some fighters fleeing a six-month-old security push in Baghdad have sought refuge in the area, U.S. commanders said. And while U.S. forces here and in other parts of the country are working with tribes that have turned against al-Qaeda in Iraq, loyalties are often fickle in this region.

"Any group you work with can turn on you," said Williams, the tribal liaison, noting that even Iraqi police units have attacked U.S. troops. "That is part of the operating cost."

Unlike in Iskandariyah or Musayyib, U.S. troops seldom patrol in remote, isolated Sunni areas. The rough terrain and the bombs peppering the roads present formidable barriers. Extremists can find havens in villages and farms.

"We haven't seen many of them yet," said Murphy, the lieutenant in the cemetery, referring to al-Qaeda fighters. "They have a great early warning system."

Increasingly, U.S. forces are launching helicopter missions into these areas to learn the terrain and establish a foothold. "It's detective work," said Lt. Col. Valery Keaveny, commander of the 3rd Battalion, 509th Parachute Infantry Regiment.

But even before their mission to Khidr, frustration ran deep among his soldiers, who have spent months chasing a hard-to-define enemy.

"We haven't done anything here. We'll go for 24 hours and we'll see nothing," said Sgt. Josh Claeson, a radio operator, as he waited with nearly 200 soldiers under the glow of an orange moon for helicopters to Khidr. "Our basic mission here is to drive around and get blown up."

At the cemetery the next morning, after the discovery of the weapons cache, a soldier picked up one of the guns and raised it triumphantly. "Hey, we are heroes," he declared, posing for a camera.

By the end of the day, the search would yield a few more weapons, including an antiaircraft machine gun, and commanders would declare the mission a success.