MOSUL, Iraq -- The two dozen Iraqi soldiers marched in formation into downtown Mosul, streets emptying in their path. The men trained their rifles on potential bomb threats: a donkey-drawn vegetable cart, a blue Opel sedan, a man with a bulge beneath his tattered gray coat.

Less than a month ago, U.S. forces patrolled these dangerous streets. But on this humid morning there were only the Iraqis and a lone U.S. adviser, Marine Staff Sgt. Lafayette Waters, 32, of Kinston, N.C., who blended unobtrusively into the patrol.

This is Area of Operations Iraq, slightly more than two square miles in the heart of Iraq's third-largest city. It is also at the center of the U.S. military's strategy to hand off counterinsurgency operations to Iraqi security forces and ultimately draw down the number of American troops.

Since Iraq's Jan. 30 parliamentary elections, that process has accelerated much more rapidly than U.S. commanders have previously acknowledged. Although AO Iraq is one of just two sectors currently under Iraqi control (the other is the area around Baghdad's Haifa Street), two senior U.S. officers said the Iraqis' zone of responsibility would soon expand and eventually include all of Nineveh province, including Mosul and Tall Afar, another volatile city, possibly within a year.

The officers cautioned that the rough timetable for the northern province's handover could be affected by several factors, including the potency of the insurgency and the preparedness of specific units. U.S. commanders have declined to provide a schedule for shifting responsibility to Iraqi forces throughout the country. But the process in Mosul, where in November insurgents overpowered an 8,000-man Iraqi police force and several National Guard units, demonstrates how fast the transition is happening.

Col. Robert B. Brown, commander of the 1st Brigade, 25th Infantry Division (Stryker Brigade Combat Team), which conducts combat operations throughout northern Iraq, predicted the transition would come "over the next six months to a year ... until pretty soon they've got the whole area and we do nothing but respond" to emergencies.

The ambitious strategy is being questioned by some U.S. military advisers who work closely with the Iraqi forces. They say that although the Iraqis are progressing, they are being rushed into battle before they are ready to speed the withdrawal of American forces.

"It's all about perception, to convince the American public that everything is going as planned and we're right on schedule to be out of here," said one adviser, Army Staff Sgt. Craig E. Patrick, 40, a reservist from Rock Island, Ill. "I mean, they can [mislead] the American people, but they can't [mislead] us. These guys are not ready."

Waters, who has lived with the 23rd Iraqi Battalion's 1st Company since Jan. 15, said that the Iraqi soldiers "have a lot of heart and are making progress" but that "we need to slow it down and do it right. The worst thing that could happen is to have to come back in and fix the problem."

The Iraqi forces are still poorly equipped, U.S. advisers and Iraqi soldiers agreed. Most ride into battle in "Road Warrior"-like white Nissan pickup trucks with machine guns welded into the bed and makeshift armor supported by plywood and even cardboard. Iraqi units lack medics, adequate communications equipment, computers and other battlefield necessities.

"This is the 21st century," said Lt. Col. Raad Abdul Hassan, an Iraqi company commander with the 23rd Battalion. "It's shameful what we have."

But senior U.S. officers maintain that the Iraqi forces have made enormous strides since the elections, playing a pivotal role in containing the insurgency in Mosul, and are now ready to take the next step.

"I think what will happen over the course of the next year is you'll see that AO Iraq, which is just the center of the city, will gradually keep expanding," said Marine Lt. Col. Russ Jamison, the senior U.S. adviser for the Iraqi army's 6th Brigade, an elite unit that commands the Iraqi-patrolled sector. "The critical piece is, at what point do we let the American unit go?"

Jamison said U.S. expectations about the capabilities of the Iraqi forces were changing dramatically.

"We're moving in the right direction," he said. "I didn't think an Iraqi battalion would have its own AO by 1 March. In fact I was very hesitant about it. When you see an Area of Operations, that means something. If you believe words mean things, then that's a level of expectation."

In a sign of AO Iraq's importance to the U.S. strategy, the 6th Brigade received a parade of dignitaries and senior officers last week. They included Lt. Gen. David H. Petraeus, who is responsible for the development of Iraqi security forces and sat for a 30-minute presentation on the brigade's progress.

"For one of your battalions to be given your own area of responsibility is a tremendous vote of confidence," Petraeus told a group of officers seated around a long table at a base that recently housed American troops.

But Iraq's 6th Brigade's performance in Mosul reveals not only how fast the process is moving but also how complicated it can be. "The learning curve looks like a lightning bolt," said Marine Capt. Jay Kajs, senior military adviser to the brigade's 24th Battalion.

The 6th Brigade, deployed to Mosul for the January elections, was expected to stay no later than Feb. 15. But shortly after the elections, the unit received new orders. Instead of returning to its base near Baghdad, the brigade's 22nd, 23rd and 24th battalions were assigned to provide security in Mosul, even as American units were leaving. The 22nd and 24th battalions were to share sectors with American units but often work alone or with limited U.S. support. The 23rd was given its own area in what commander Brown acknowledged was an experiment that had many doubters.