Preparing for a morning patrol, Sgt. Adam Brantley surveyed his perch in the gunner's nest of an armored Humvee. In front of him was a machine gun mounted on a swivel. His M-4 rifle lay on the roof next to it.

Brantley stepped down and stooped in the dust, searching for rocks the size of baseballs. He collected a few handfuls and piled them next to his rifle. His convoy pulled into the smoky streets of Sadr City.

"I don't throw unless thrown upon," said Brantley, 24, who would have cause to do so in the next few hours as rocks thrown from side streets banged against the Humvee.

In the context of Iraq's continuing violence, it is perhaps a measure of progress that U.S. soldiers working in a slum on Baghdad's barren eastern edge are feeling the sting of stones more often than bullets. Only weeks ago, U.S. soldiers were fighting -- and, in some cases, dying -- to put down an armed Shiite uprising on the same streets.

But the daily rock fights between U.S. soldiers and ordinary Iraqis, many of them children, highlight the mutual antipathy that has built up since the handover of political power to an Iraqi government. Although often-intense fighting continues in some regions, the U.S. military occupation of Sadr City, as observed in four days on patrol with a U.S. Army unit, has evolved into a grinding daily confrontation between frustrated American soldiers and a desperate population.

After 15 months of halting progress on U.S.-funded reconstruction projects, many Iraqis who once supported the U.S. invasion are resisting the military occupation, a fight that features gangs of impoverished children as an angry, exasperating vanguard. The strain of the hostility on U.S. soldiers is palpable and poses huge risks to the completion of millions of dollars in reconstruction work designed to help stabilize Iraq.

In heat that hovers near 115 degrees, troops overseeing projects to bring clean water to neighborhoods awash in raw sewage are greeted by jeering mobs. Swarms of teenagers and children pump their fists in praise of Moqtada Sadr, the Shiite cleric whose militia has killed eight soldiers and wounded scores more from the 1st Cavalry Division battalion responsible for Sadr City's security and civic improvement. In April, during an uprising in Sadr City, the division estimated that it killed hundreds of Sadr's militiamen.

Candy, once gleefully accepted in this part of Baghdad, is now thrown back at the soldiers dispensing it.

The military partnership with new Iraqi security forces appears to be foundering on a mutual lack of respect. The Iraqi police occasionally ignore U.S. orders, described as recommendations by U.S. commanders in the days since the handover, to conduct night patrols in troublesome districts and prohibit Sadr's militants from manning traffic checkpoints. The Iraqi National Guard has refused dangerous assignments, even when accompanied by U.S. troops.

Lt. Col. Gary Volesky, commander of the division's 2nd Battalion, 5th Cavalry Regiment of the 1st Brigade in Sadr City, said there was much to be done to demonstrate to the Iraqi people that the Army has come to help them. "We've been here a year and they haven't seen much progress," he said. "That's our challenge."

Volesky, an energetic commander admired by his troops, delivered that assessment one recent morning from the roof of the Karama police station. Bombed by Sadr militants in June, the two-story building appears at the moment to be defying gravity. The facade lies in rubble, and the exposed second-story floor sags like an old mattress.

Volesky was making a keep-your-chin-up visit, and the Iraqi police officers appeared surprised to see him. They escorted him through the wreckage of the building, which has no electricity and which his soldiers once took back from Sadr militants after a fierce firefight. Then he headed to the roof.

Almost at once, rocks began falling around him, skittering across the rooftop. In the distance, a young boy leaned back to throw again. But his stone fell short. "You're going to need more than that," Volesky said to the boy.

"As you can see, this is not the friendliest neighborhood," he said. But he noticed three men on a nearby street corner, gesturing for the rock throwers to leave.

"Thank you," Volesky shouted to them in Arabic. "Thank you very much."

Then he said, "Let's go talk to those guys."

As soon as Volesky left the ruined station, he was confronted by crowds of children and a few men working in a strip of auto repair shops next door. They wanted to know why their electricity was off more often than on, something U.S. soldiers struggle to determine on a daily basis. Electricity in Baghdad's summer heat means air conditioning, and a cooler population is a happier one.

"We've started fixing your sewers," said Volesky, who had just passed a pipeline project that will pump some of the green sludge from the streets. "Soon you'll see it coming this way."

The children gathered in a rowdy scrum around the soldiers. A chubby kid poked at them, then opened his mouth to wiggle a very loose tooth in their faces. A gunshot popped in the near distance, putting the soldiers on alert. A thin, dark child dressed in filthy clothes began to chant, "Moqtada, Moqtada, let's go, let's go, Moqtada." Others joined in, shuffling their feet in a two-step dance.

As the soldiers packed into Humvees and pulled away, stones clattered against the armor.

"That's all you got, just those little pebbles," said a soldier driving one of the Humvees.

Sgt. Timothy Kathol, 24, of Amarillo, Tex., handed a bag of lollipops up to the gunner as the stones continued to rain down. "They throw rocks, we throw candy -- really hard candy," Kathol said. "With sticks in it."

Battle to Provide Basics

Sadr City, home to at least 2 million poor people, has been a miserable place for decades. President Saddam Hussein's Sunni-led government deprived the Shiite neighborhood, once a pocket of political resistance, of most basic services. Reliable electricity, working sewers and clean drinking water have always been scarce.

When U.S. troops toppled Hussein last year, the neighborhood celebrated. But now U.S. troops working to improve basic services appear to be bearing the blame for a grim history. In their view, the people seem unwilling to help themselves.

"I love the smell of sewage in the morning," Kathol said as his Humvee left Camp Eagle, the Army post on Sadr City's northern edge, and was engulfed by the slum's signature stench.

"Smells like victory," replied Pfc. Joseph Crosier, 23, of Syracuse, N.Y., continuing the reference to a speech in the movie "Apocalypse Now."

In the movie, napalm smelled like victory. The smell in the Humvee was coming from a large, swampy pond of sewage where people were bathing in the intensifying morning heat.

In earlier years, roving animals were let loose on large piles of street-side garbage. Today, sheep still graze on median-strip trash, and a hundred fires reduce what remains into black, greasy piles, casting a hazy pall over the streets.

A couple of months ago, during the Sadr uprising, the battalion launched Operation Iron Broom -- a street-cleaning, garbage-collection program that cost several hundred thousand dollars. It was carried out by U.S. soldiers at a time when their colleagues were being wounded in the same streets by Sadr militants. After days of tedious work, many of the streets were as clean as they'd ever been and large steel dumpsters dotted the medians, soldiers recalled.

Within days, the dumpsters had disappeared. Neighborhood residents had cut off the lids for use as garage doors. They sold the rest for scrap in ramshackle stalls piled with mufflers, gas tanks and other debris. Soldiers have since helped build concrete receptacles in the medians, but there is far more trash outside them than in. A public awareness campaign on how to use them is being prepared.

"If they spent half as much time on trash cleanup and these projects as they do trying to blow us up, this would all be fixed by now," said Crosier, who has been hit by three roadside bombs and suffered severe burns.

Taking the Community Pulse

On a recent morning, Lt. Raymie Walters headed out with Alpha Company's 3rd Platoon to take some popular soundings. The soldiers and the military intelligence officers back at the post use a variety of unscientific methods to measure the sentiments and general health of the community. Security, quite literally, has to do with the price of eggs.

Walters, 26, of Longview, Wash., took a column of Humvees to a market to check on food prices, which often fluctuate with insurgent activity. The convoy pulled up to a stall and the soldiers got out. But they had no interpreter. After a few minutes of holding up Iraqi dinars, pointing to produce and flapping like a chicken, Walters had his price list.

The children emerged from nowhere. "Moqtada, Moqtada," they began taunting.

Staff Sgt. Matthew Mercado, 27, of Jonesboro, Ark., shook his head as the Humvees pulled away. "You see what happens when we just ask for the price of a banana?" he said.

The convoy sped down a wide avenue. Down small alleys, scurrying kids came into view with rocks in their hands. A stone bounced short of the Humvee, leaping up to peg the door. Walters told Mercado to radio the rest of the convoy with a warning for the gunners to keep low.

That evening, U.S. commanders drew up plans for a foot patrol, matching a platoon of U.S. soldiers with two squads of Iraqi National Guard troops. The mission entailed setting up ambush positions along the road leading from camp into the center of Sadr City, a route where roadside bombers frequently operate. There they would wait for the men planting the explosives or flush them out by using illumination rounds to draw fire. But the mission was delayed an hour, then canceled. U.S. commanders said the Iraqi troops refused to participate.

"They don't want to work," said Lt. Derek Johnson, 25, of Driggs, Idaho. "But they still want our money."

Johnson, commander of Alpha Company's 1st Platoon, had a long morning ahead of him the next day policing the police. As Bradley Fighting Vehicles and Humvees idled, he and his men waited for 15 Iraqi soldiers to join the patrol, then waited even longer for a "psy ops" team with anti-Sadr pamphlets to hand out.

The Iraqi soldiers piled into two Bradleys, carrying AK-47 assault rifles and wearing new body-armor vests. They took turns tapping each other on the chest plates as they waited to leave.

Johnson's task was to make sure the Iraqi police had set up checkpoints in designated spots and were manning them without help from Sadr's Mahdi Army militia or any other civilians. The first intersection was empty of police, and the second was being worked by a group of men wearing matching blue-and-white soccer jerseys. They had whistles. The drivers obeyed them. But they were not the police -- who sat inside their station a block away -- and were likely Sadr militants.

"We're from the neighborhood," said one sweaty man in a Tommy Gear cap.

"According to their interim government, it's not allowed for any uniformed personnel other than Iraqi police to man these checkpoints," Johnson warned through an interpreter. "I'll be coming back here, and I don't want to see them."

Johnson did return a few hours later. The men had not left.

Children, the vanguard of the new resistance in Sadr City, taunt and harass U.S. soldiers patrolling with Iraqi forces.Lt. Col. Gary Volesky of the 1st Cavalry Division meets with Iraqi police and National Guard officers to coordinate patrols and checkpoints throughout the Baghdad slum of Sadr City.