So a platoon of American troops drove up a bomb-cratered road in their Stryker vehicles on Thursday to give the Iraqis some pointers on how to hold the line. After the ramps of the Strykers were lowered, Second Lt. Adam Bowen sought out his Iraqi counterpart at the battered storefront in the Thawra district that served as an Iraqi strongpoint. "Are you going to stay?" the Iraqi lieutenant asked hopefully. Lieutenant Bowen told them his platoon was not. Surveying the terrain, he recommended that the Iraqi soldiers set up a firing position overlooking a sniper-infested alley. After an hour, the Americans headed back to the abandoned house that served as the company command post, and the gunfire in the streets picked up again. The struggle for control of Sadr City is more than a test of wills with renegade Shiite militias. It has also become a testing ground for the Iraqi military, which has been thrust into the lead. Iraqi soldiers, suffering from a shortage of experienced noncommissioned officers, have often been firing wildly, expending vast quantities of ammunition to try to silence militias that are equipped with AK-47's, mortars and rockets. But pulling back from their positions earlier, they now appear to be holding their ground albeit with considerable American support. Iraqi politics has played a role in shaping the military strategy. Prime Minister Nuri Kamal al-Maliki has decreed that American ground forces should not push into the heart of Sadr City, according to a senior American officer. American commanders also want to limit the United States' profile in an area that has long been a bastion of support for Moktada al-Sadr, the anti-American cleric. But American commanders also see this as an opportunity to shift more responsibility to the Iraqi troops in this case Iraq's 11th Army Division, one of the newest divisions in the Iraqi military. Whether they like it or not, Iraqi troops are hundreds of yards ahead of the farthest American position and in the thick of the fight. "The I.A. needs to start doing it on their own," Lieutenant Bowen, the 23-year-old commander of Third Platoon, Bravo Company, told a reporter who accompanied him on the mission, referring to the Iraqi Army. The Iraqi troops, of course, still benefit mightily from American military support. On Thursday morning, Apache helicopters fired Hellfire missiles at teams of militia fighters that were preparing to fire mortars. Heavily armored American "route clearance" vehicles, their searchlights blazing in the night, swept the roads for hidden bombs. An American reconnaissance drone buzzed overhead and an armed Predator drone blasted a small group of militia men a few days ago. In an urban battlefield in which there are often no clear lines and militias still roam the narrow side streets, American soldiers are very much at risk and in the fray. On Wednesday at dusk, Lt. Marc Dudek, the leader of Second Platoon, which was defending the forward line of the American forces here, led his soldiers into the street after a rocket-propelled grenade flew past the abandoned house where his troops had pitched camp. As the soldiers returned to their house after a fruitless search, the civilians ominously vanished from a side street. The platoon took fire from a nearby building moments later and responded with an ear-shattering barrage. That quieted the militias for a while. By nightfall, the shooting started again. The Thursday mission by Lieutenant Bowen was to check on the Iraqi forces who were defending an intersection 300 yards north of Lieutenant Dudek's position. Both platoons are part of the First Battalion, Fourteenth Infantry Regiment, and were based near Taji before they were rushed to Baghdad to help with the Sadr City operation. The soldiers were told that they might be needed in Sadr City for a few days. Instead, they have been here for almost two weeks and are now preparing to stay longer. The Americans' working relationship with the Iraqis is professional but not always clear. "There is no good liaison right now between the I.A. and the coalition forces," Lieutenant Bowen said. "It makes things kind of confusing to come up here not knowing exactly what you are getting yourself into tactical-wise. So you come up, figure out what the tactical situation is and try to push through from there." As the Iraqi and American officers huddled, the Iraqi lieutenant said some of his soldiers had been receiving threatening calls on their cellphones from members of the Madhi Army warning them to leave. The Iraqi lieutenant could not say how the Mahdi Army obtained their phone numbers, but some Iraqi soldiers who participated in the Basra fighting deserted after their families were threatened.