RAMADI, Iraq -- This palm-lined city along the Euphrates, once a deadly stronghold of the insurgency, has been hailed as one of Iraq's greatest turnaround stories, the first major urban area where militants were driven back and life slowly returned to shattered neighborhoods.

But a rift has opened in recent weeks between local leaders of this Sunni-dominated area and Iraqi soldiers who serve here but answer to leaders in Baghdad's Shiite-led government. Residents have accused Iraqi Army units of shooting civilians, meddling in local politics, raiding homes with little justification and detaining residents indefinitely.

The distrust, highlighted by public protests and calls for the army to withdraw, has challenged the durability of security gains in Ramadi and across the huge western reaches of Anbar, the main Sunni province and a crucial proving ground for Iraq's stability. The tensions also highlight the disputes that seem to be spreading across the country and seem likely to linger long after the last American soldiers leave: conflicts of local autonomy versus national control, sectarian power struggles and fierce debates over who, in the end, should be entrusted to keep Iraqis safe.

In mid-June, hundreds of residents filled the streets of the predominantly Sunni holy city of Samarra, in Salahuddin Province in central Iraq, to demand that a unit of Iraqi troops leave.

In Ramadi, resentments came to a boil this month after Iraqi soldiers shot and killed a local police captain who had fought alongside American Marines against Sunni insurgents fighting under the banner of Al Qaeda in Iraq. The Iraqi Army said he had been trying to flee an arrest warrant on terrorism charges, but tribal leaders and local politicians said the charges were trumped up and called him a hero whose death demonstrated the impunity of security forces in the area.

The Iraqi soldiers who guard checkpoints and rumble through the streets in camouflaged Humvees say they are preserving a hard-fought and fragile peace in Anbar. The Iraqi Army is one of the country's most trusted institutions, but many local leaders have come to see the soldiers as heavy-handed occupiers with little concern for the community -- a charge once lobbed at American troops.

"The army is interfering in schools and vegetable markets," said Sheik Faisal Hussein Essawi, one of several tribal leaders who have organized protests calling for the soldiers to withdraw. "They are everywhere. The city is turning into a military camp."

Officials with the Anbar Operations Command, an Iraqi force that oversees security in the province, defended the army's role. They said that corrupt and incompetent local police had failed to prevent bombings and pursue militants in cities like Ramadi and Falluja, forcing Iraqi soldiers to move in over the past eight months.

Anbar's fate is critical both to Iraqis and the departing American forces. According to icasualties.org, some 1,335 American service members were killed here, as well as untold thousands of Iraqi civilians, soldiers and members of the American-backed Awakening militias that fought Al Qaeda in Iraq.

At least 3,200 American troops remain, though they have largely pulled out of the cities and focus on training Iraqi security forces and helping local leaders and commanders address flaws in security.

Violence edged higher as the latest tensions flared. This month, insurgents planted four explosives at a police commander's house outside of Falluja, killing four of his relatives. Days earlier, suicide bombers killed 15 people in an attack on security forces in Ramadi.

Col. Louis J. Lartigue of the United States 4/3 Advise and Assist Brigade in Anbar said the increase appeared to fit a pattern of spikes and lulls in attacks. He said he was encouraged that local politicians and military leaders were at least sitting down to discuss their differences.

"When they do have these problems, they come forward to figure out what the best way ahead is," he said. Control of Iraq's cities is a central issue in a country where two-thirds of the people live in urban areas. As Iraq stabilizes, army units are supposed to withdraw and focus on weak points in national defense, like border security, and cede the cities to the national and local police.

After protests erupted in Anbar, the army acquiesced to some of the residents' demands, saying it would withdraw troops from the center of Ramadi. But an official with the Anbar Operations Command, who asked not to be named because he was not authorized to speak with reporters, predicted a surge in violence if soldiers were relegated to their bases or to patrolling Iraq's vacant western borders.

"We'll put the police back in charge, and you'll see what happens," the official said. "If they see someone's relative is a terrorist, they won't report it." He said that the Iraqi Army had pursued only legitimate targets, and fired only on suspects who posed a threat.

But local leaders seethe over what they call the Iraqi military's excessive use of force.

Maj. Majid Salim, a deputy police chief, said army troops did not coordinate arrests with the local police, and had destabilized security by eroding the relationship between residents, tribal sheiks and security officials.

In October, Iraqi troops killed a 12-year-old girl and an elderly man in a raid to arrest a former security officer suspected of terrorism. Two months ago, soldiers shot and killed a driver in what the local police called a dispute over where the man had parked his car. Security officials said they had a warrant for his arrest.

And this month, a truck carrying Iraqi soldiers drove to the farm of Hamid Ahmed Shahab, a local police commander, to arrest him on a 2009 terrorism warrant, which American officials confirmed was valid. When Mr. Shahab bolted for his car, soldiers shot him in the back.

The Iraqi Army would not identify the charges against Mr. Shahab, but they said they found two guns in his car. The Iraqi military official called his killing "the right thing" to do.

But his death deepened the distrust and discord between military officials and tribal leaders, and touched off several protests. Mr. Shahab's relatives said the Iraqi Army had killed a brave police captain who had lost two brothers to Qaeda attacks, then joined American forces to hunt down insurgents in 2007.

Two Marines who fought among the palm groves and irrigation canals of the village of Juayaba, just outside Ramadi, confirmed the relatives' version of events, saying that Mr. Shahab -- also known as Abu Ali -- played a critical role in leading a tribal revolt against Al Qaeda that gained momentum and spread.

"He basically created this revolution on his own," said Capt. Thomas P. Daly, who chronicled his tour in Anbar in "Rage Company," a memoir. "I can name terrorists that this guy killed. This dude hated Al Qaeda. He hated them with a passion."

Mr. Shahab linked up with a Marine company in early 2007 and began accompanying them -- sometimes leading them -- on raids to capture Qaeda suspects, the Marines said. He recruited scores of other tribal fighters and helped choke off relentless bomb attacks against the Marines.

"He was instrumental in the success of that area," said Capt. Craig A. Trotter. "A true Iraqi hero for his people."

This month, a few dozen of Mr. Shahab's kinsmen gathered near a security checkpoint to demand justice for his death. Security forces stood at the ready, but let the men demonstrate.

After about an hour, and slightly disappointed by the turnout, the men climbed into their cars and drove off. A few hundred yards away, at the entrance to the city, a banner greeted visitors with the words, "Ramadi was and always will be a city of peace."

First Published: June 27, 2011, 4:00 a.m.