Abu Ali, a community leader in a white dishdasha, walked into the Americans' battle-scared combat outpost with an unusual proposal: He wanted their help in taking on Al Qaeda extremists who have taken over the area.

The April 7 meeting was the beginning of a new alliance and, American commanders hope, a portent of what is to come in the bitterly contested province of Diyala.

Using his Iraqi partners to pick out the insurgents and uncover the bombs they had seeded along the cratered roads, Richards's soldiers soon apprehended more than 100 suspected militants and several low-level emirs. The Iraqis called themselves the Local Committee. Richards has dubbed them the Kit Carson scouts.

"It is the only way that we can keep Al Qaeda out," said Richards, who operates from a former police station in the Buhritz sector of the city that still bears the sooty streaks from the day militants set it on fire last year.

Al Qaeda in Mesopotamia, a predominantly Iraqi organization with a small but significant foreign component, was deeply resented by many residents and other insurgent groups, people who live here said. Imposing a severe version of Islamic law, the group had installed its own clerics, established an Islamic court and banned the sale of cigarettes, which even this week were nowhere to be found in the humble shops in western Baquba.

The fighters raised funds by kidnapping locals, found accommodations by evicting some residents from their homes and killed with abandon when anyone got in their way, residents said. A small group of bearded black-clad militants took down the Iraqi flag and raised the banner of their self-proclaimed Islamic State of Iraq.

"They used religions as a play to get in and exploit peoples' passions," said a member of the Local Committee who gave his name as Haidar. "They were Iraqis and other Arabs from Syria, Afghanistan, Jordan, Saudi Arabia and Egypt. They started kicking people out of their houses and getting ransom from rich people. They would shoot people in front of their houses to scare the others."

The residents' antipathy toward their Islamic occupiers took an unexpected turn soon after Richards's soldiers arrived in March as part of a battalion-sized operation. Unlike many earlier operations, the Americans showed up in force and did not quickly withdraw. The residents saw an opportunity to challenge Al Qaeda of Mesopotamia, and for a week, the two sides battled it out in the streets.

Initially, the Americans stood on the sidelines, concerned that they might be witnessing nothing more than a turf fight among insurgents and militias.

"We were not sure what was going on," Richards recalled. "We were not sure we could trust the people not to turn on us afterwards."

But after the militants gained the upper hand and more than 1,000 residents began to flee on foot, the Americans moved to prevent the militants from establishing their control throughout the neighborhood. The soldiers called in an airstrike, which demolished a local militant headquarters.

The meeting between the residents and the Americans was Ali's initiative. The locals wanted weapons to carry on their fight. Richards had another proposal: The residents should tip off the Americans on which Iraqis belonged to Al Qaeda of Mesopotamia and where they had buried their bombs, vital battlefield intelligence American and even Iraqi troops needed to pursue their offensive. At first, no more than a dozen of the several hundred Sunnis who were taking on the militants served as Kit Carson scouts, but they made a vital difference.

The American military has struggled for more than four years to train and equip the Iraqi Army. But here local Sunni residents, including a goodly number of former insurgents from the Revolution Brigades, have emerged as a linchpin of the American strategy.

The coalition reflects some hard-headed calculations on both sides. Eager for intelligence on their elusive foes, American officers have been willing to overlook the insurgent past of some of their new allies. Many Sunnis, for their part, are less inclined to see the soldiers as occupiers now that it is clear U.S. troop reductions are all but inevitable, and are more concerned with strengthening their ability to fend off threats from militias who plague the province.

Collaborations like this are slowly beginning to emerge in other parts of Iraq. In Baquba, at least, they face some notable obstacles, primarily from the Shiite-dominated provincial and Baghdad ministries that are worried about American efforts to rally the Sunnis and institutionalize them as a security force.

But with the government of Prime Minister Nuri Kamal al-Maliki showing scant progress toward political reconciliation and the U.S. military eager to achieve a measure of stability before troop levels begin to fall back, American commanders appear determined to proceed with this more decentralized strategy - one that relies less on decisions made by Iraqi leaders in Baghdad and more on newly forged coalitions with local Iraqis.

The strategy is especially important for the current stage of military operations in Baquba, in which the emphasis is no longer on clearing houses, but on uncovering hidden cells of militants and preventing insurgents from outside the city from sneaking back in.

"Up until Captain Richards went in, we fought," recalled Lieutenant Colonel Mo Goins, the commander of the 1st battalion, 12th Infantry Regiment, which for six months operated single-handedly on some of the toughest battlefields in Diyala. "That is what we did. Small arms. Mortars. IED's.

"We did some humanitarian drops. Tried to find the muktars," he added, referring to neighborhood powerbrokers. "Never succeeded. Not like now."

Richards, an native of Idaho and a former Mormon missionary, commands Bronco Troop, 1st Squadron, 14th Cavalry Regiment. When the 31-year-old officer was first sent to Buhritz in mid-March as part of a battalion-sized task force, he encountered a deeply entrenched foe, numbering in the thousands.

Many of the Al Qaeda in Mesopotamia members were ensconced in a sprawling Palm Grove-laden sanctuary south of Baquba and east of the Diyala River. The area, which is still under the group's control, is still so replete with arms caches, insurgent leaders, fighters and their supporters that American soldiers have taken to calling it the "Al Qaeda FOB," or forward operating base in American military jargon.

The insurgents also had a firm grip on the city, the provincial capital of Diyala, which Abu Musab al-Zarqawi made the center of his self-styled Islamic caliphate before he was killed in an airstrike near Baquba last year. The key supply and communications lines between the insurgents' rural staging area and the city ran through the Buhritz, making it vital ground for Al Qaeda.

The militants' hold on the region was facilitated, senior U.S. officers now acknowledge, by a decision to draw down forces in the province in 2005 in the hopes of shifting most of the responsibility for securing the region onto the Iraqis. That strategy backfired when the Iraqi authorities appointed overly sectarian Shiite army and police regional commanders, alienating the largely Sunni population.

The Americans did have one thing going for them - Al Qaeda of Mesopotamia had severely overplayed its hand.

Unlike Anbar Province, where the American military has formed similar alliances, Diyala lacks a cohesive tribal structure. Nor did another Sunni insurgent group, the 1920s Revolutionary Brigade, deliver fighters en masse. But the welter of movements and sectarian fault lines in Diyala is more representative of many parts of Iraq than the far west.

Even so, some of the main obstacles the Americans have faced in institutionalizing the arrangement with the scouts have come from the Iraqi government. According to Richards, the provincial police chief, Major General Ghanen al Kureshi, repeatedly resisted efforts to hire the local Sunnis, arguing that they had failed to express interest in a police post when they had the chance.

Richards rejected a group of Shiite police recruits from Baghdad, fearing some might belong to Shiite militias. Determined to get his scouts hired, he loaded 50 of them on his Stryker vehicles and drove them to the provincial headquarters over the insurgent-threatened roads.

Today, the police number only 170, a fraction of the police force in adjoining areas. The small force was provided with only two trucks, seven radios and a paltry supply of ammunition, which the Sunni residents have managed to supplement by buying ammunition on the black market from corrupt Interior Ministry officials in Baghdad. Another 150 scouts participate as unpaid monitors in a neighborhood watch program to guard key routes in and out of the area that Richards oversees.

Referring to Ghanen, the provincial police chief, Richards said, "the people in the community think that he is actively trying to prevent the Buhritz police from establishing themselves, because the Shia government does not want a legitimate Sunni security force in Diyala province."

Goins had a more charitable view of the provincial chief's actions, saying he wanted to hire many more police for Baquba but was coping with personnel and weapons shortages, as well as Interior Ministry guidance to build up the force in other areas. "Right now, his resources are extremely limited," Goins said.

The new police and neighborhood watch monitors appear to work well with the local Iraqi Army unit and police officials. But a local Iraqi Army commander openly expressed doubts that the scouts, in uniform or not, amounted to a disciplined, military unit that could take and hold ground.

During a quick visit to two villages, Gu'am and Abu Fa'ad, the Americans and their Iraqi allies tried to persuade welcoming but still wary residents that they needed to overcome their fears of Al Qaeda and provide tips for their own security. The American military is also trying to expand the alliance into the western sector of the city, which it recently wrested back from Al Qaeda militants.

During the recent American assault in western Baquba, soldiers from Blackhawk Company got a glimpse of an alliance the Americans hope to see. An Iraqi seemingly emerged from nowhere, announced himself as a member of the 1920s Revolutionary Brigades and warned the soldiers that insurgents could be found on the far side of a sand berm around the corner. The tip was accurate.