BAGHDAD, Iraq -- In the battle for Baghdad, Haifa Street has changed hands so often that it has taken on the feel of a no man's land, the deadly space between opposing trenches. As American and Iraqi troops poured in yesterday, the street showed why it is such a sensitive gauge of an urban conflict marked by front lines that melt into confusion, enemies with no clear identity and allies who disappear or do not show up at all.
In a miniature version of the troop increase that the United States hopes will secure the city, American soldiers and armored vehicles raced onto Haifa Street before dawn to dislodge Sunni insurgents and Shiite militias that have been battling for a stretch of ragged slums and mostly abandoned high-rises. But as the sun rose, many of the Iraqi army units that were supposed to search the buildings did not arrive on time, forcing the Americans to start the job on their own.
When the Iraqi units finally did show up, it was with the air of a class outing, cheering and laughing as the Americans blew locks off doors with shotguns. As the morning wore on and the troops came under fire from all directions, another apparent flaw in this strategy became clear as empty apartments became lairs for gunmen who flitted from window to window and killed at least one American soldier, with a shot to the head.
Whether the gunfire was coming from Sunni or Shiite insurgents or militia fighters or some of the Iraqi soldiers who had disappeared into the cityscape, no one could say.
"Who the hell is shooting at us?" shouted Sgt. 1st Class Marc Biletski, whose platoon was jammed into a small room off an alley that was being swept by a sniper's bullets.
Just before the platoon tossed smoke bombs and sprinted through the alley to a more secure position, Biletski had a moment to reflect on this spot, which the United States has fought to regain from a mysterious enemy at least three times in the past two years.
"This place is a failure," he said. "Every time we come here, we have to come back."
The Haifa Street operation is likely to cause reflection by commanders in charge of the Baghdad "surge" of more than 20,000 U.S. troops. Just how the troops will be used is not yet known, but it is likely to mirror the Haifa Street strategy of working with Iraqi forces to take on unruly groups from both sides of the Sunni-Shiite sectarian divide.
The operation's commander, Lt. Col. Avanulas Smiley of the 3rd Stryker Brigade Combat Team, said his forces were not interested in whether bullets were fired by Sunnis or by Shiites. He conceded that the cost of letting Iraqi forces learn on the job was to add to the risk.
"This was an Iraqi-led effort, and with that come challenges and risks," he said. "It can be organized chaos."
American units began moving up Haifa Street by 2 a.m. A platoon secured the roof of a high-rise, where an Eminem poster was stuck on the wall of what appeared to be an Iraqi teenager's room on the top floor. But in a pattern that would be repeated again and again in a series of buildings, there was no one in the apartment.
Many of the Iraqi units never seemed to take the task seriously, searching haphazardly, breaking dishes and rifling through CD collections in the apartments. Eventually, the Americans realized that the Iraqis were searching no more than half the apartments; at one point the Iraqis disappeared, leaving the American unit working with them flabbergasted.
"Where did they go?" yelled Sgt. Jeri A. Gillett. Another soldier suggested, "I say we just let them go and we do this ourselves."
Then the gunfire began. It came from high-rises across the street, from behind trash piles and sandbags in alleys and from so many other directions that the soldiers began to worry that the Iraqi soldiers were firing at them. Mortar rounds started dropping from across the Tigris River, in the direction of a Shiite slum.
The only thing that was clear was that no one knew who the enemy was. "The thing is, we wear uniforms - they don't," said Spc. Terry Wilson.
At one point the Americans were forced to jog alongside the Strykers on Haifa Street, known as "Sniper Alley," sheltering themselves as best they could from the gunfire. The Americans finally found the Iraqis and ended up accompanying them into a dangerous warren of low-slung hovels behind the high-rises as gunfire rained down.
American officers tried to persuade the Iraqi soldiers to leave the slum area for better cover, but the Iraqis refused to risk crossing a lane that was being raked by machine gun fire.
"It's their show," said Lt. David Stroud, adding that the Americans have orders to defer to the Iraqis in cases like this.
In this surreal setting, the American soldiers were stunned when a small child suddenly walked out of a darkened doorway. One Iraqi soldier in the alley pointed his rifle at an American reporter and pulled the trigger. There was only a click: The weapon had no ammunition. The soldier laughed at his joke.