SAMARRA, Iraq - Cities around Iraq are taking advantage of improved security to rebuild neighborhoods, but here, the ruins of a revered Shiite Muslim shrine bleed seamlessly into the desolation that is this city's downtown.

Samarra shows the limits of the U.S. surge, which has brought a modicum of calm to cities such as Fallujah, Baghdad and Ramadi. No additional troops have been sent here, no Sunni leader is stepping forward to rally his forces against foreign fighters, and no promises have been made to rebuild.

The golden-domed Askariya Mosque, destroyed in a February 2006 bombing that brought simmering sectarian violence to a boil, remains closed, engulfed by untouched mountains of rubble.

Blocks of shops around it also are closed, and there are no shoppers, much less religious pilgrims.

Al-Qaeda in Iraq, which has been vanquished in much of Iraq by an alliance between U.S. troops and Sunni Muslim tribesmen, remains a power to be reckoned with. In Samarra, there has been no surge of U.S. troops and no local leader willing to take on al-Qaeda in Iraq. There are only 700 soldiers to hold this city of 90,000 residents, and the 2,000 Shiite police sent to help are widely distrusted by the residents.

"The people are waiting to see who is going to win - the coalition forces or the terrorists," said Mahmoud Abbas, the Sunni mayor of Samarra, which is predominantly Sunni. ". . . We need the support from the coalition forces the way they supported other areas."

Samarra became synonymous with Iraq's descent into violent sectarian warfare when insurgents entered the mosque in 2006 and placed explosive charges throughout the sanctuary, shattering the mosque's golden dome. This summer, other bombs toppled its two remaining minarets.

Several U.S. units have tried to turn Samarra around, the latest being the Second Battalion, 327th Infantry Regiment of the 101st Airborne Division from Fort Campbell, Ky., which deployed to Samarra on Oct. 25.

But without the additional resources other cities have gotten, there is little to show for its efforts so far. The rejuvenation elsewhere has eluded Samarra, and there is no clear force in charge. Residents say the national police, some sent here by Shiite Prime Minister Nouri al-Maliki, are arresting them for no reason and taking away their weapons.

"I think what we are doing is part of the surge," said Lt. Col. Joseph McGee, the battalion commander. "But Samarra is complicated. We have to somehow get people back to their shops."

The latest U.S. effort to turn Samarra around falls to Capt. Josh Kurtzman, 28, of Augusta, Maine, whose Charlie Company is based at a Samarra outpost.

Kurtzman, serving his third tour in Iraq, would like to build a Sunni-led force to patrol the city, as U.S. military officers have done in other parts of Iraq, so that the Shiite-led national police are guarding only the shrine and the city's periphery. He also wants to open roads that were closed by a recent spate of violence. Together, that would create an economic boom, he said.

Al-Qaeda in Iraq grew stronger in Samarra in the early months of the surge. When U.S. forces cleared Ramadi, Fallujah and nearby Baqubah of Islamic extremists earlier this year, the escaping fighters fled to Samarra.

They controlled the eastern part of the city, patrolling the neighborhoods and pushing out government forces. They recruited new fighters, sometimes forcibly, training them and sending them out to attack U.S. troops or rival Sunni factions. They paid them enough to support a family for a few weeks. In parts of the city, al-Qaeda in Iraq became a main employer.

U.S. officers say they are making gains against the Islamists. While U.S. troops are often attacked with small-arms fire and explosives, so far no battalion members have been killed in the city since arriving six weeks ago.

Instead, U.S. officials said that they killed the city's al-Qaeda in Iraq leader, Talal Abd al-Aziz, earlier this month, and that a rival Sunni group, Jaish al-Islami, was pushing out the al-Qaeda in Iraq fighters. Kurtzman said about 150 core al-Qaeda in Iraq members remained in Samarra.

But residents said they were still afraid, choosing to stay hidden in their homes rather than get caught in a battle between al-Qaeda in Iraq and Jaish al-Islami.

"I think once people believe al-Qaeda has been defeated, the reconciliation will begin," Kurtzman said. "People in this city have seen it go up before, and I think they are afraid it will go back down again."