Baghdad - A violent contest of will is taking place in Baghdad's Sadr City between US forces and Shiite gunmen of radical cleric Moqtada al-Sadr over a three-mile barrier that will cordon off the northern and southern sectors of the district and help protect the capital's government centre from rocket attacks.

Every day, 24-hours a day since April 19, US soldiers have been placing 12-foot-high concrete slabs along al-Quds Street, a broad garbage-strewn thoroughfare on the northern edge of southern Sadr City's Jamilla and Tharwa neighbourhoods.

Every day, usually in the late afternoon and early evening, snipers from al-Sadr's Mahdi Army, or Iranian-influenced "special groups" linked to it, open fire on the soldiers in an attempt to stop or at least slow down ­the building of the barrier.

"We've had RPGs (rocket propelled grenades) coming at us, we've been sniped, all of that stuff, but we continue putting in the wall," said 1st Sergeant Conrad Gonzales, of Charlie Company, 1st Battalion, 68th Armor Regiment.

"Every day we get attacked, we still put in barriers. The mission has to go on, it has to be accomplished. We can't let anyone stop us."

Sadr City is a teeming slum of 2.5 million people in north-east Baghdad. It's the stronghold of al-Sadr, a political rival of Iraqi Prime Minister Nouri al-Maliki.

In March al-Sadr, who is believed to be currently in Iran, called off a ceasefire between his militia - known as Jaish al-Mahdi (JAM) - and the Iraqi Security Forces (ISF) and US troops in anger over the government cracking down on Shiite militants, including his own gunmen, in the southern city of Basra.

Dozens of 107mm and 120mm rockets began to rain down on Baghdad's so-called International Zone, the location of national government offices and US military and diplomatic missions, from southern Sadr City. JAM also launched coordinated attacks on Iraqi military posts in the district.

The insurgents were pushed back from Jamilla and Tharwa with US help, but now US troops have outposts in the sector from which they work jointly with Iraqi soldiers or independently in eliminating the gunmen and thus loosening al-Sadr's grip on the population.

Work on the wall began April 19 and will be completed by the end of May at the latest. Soldiers say they have already laid down nearly half of the 2,100-2,400 concrete slabs that will block entry to the Tharwa and Jamilla neighbourhoods from the north through the many cross streets along al-Quds Street.

Three crossings, however, will be open, and those crossings have Iraqi Army and police checkpoints where vehicles are searched for weapons and munitions.

Between April 19 and May 2, US forces logged at least 66 attacks against them along the wall. In addition, they detected 48 improvised explosive devices (IEDs) planted along the wall route.

Two US soldiers have been wounded putting up the barrier, while 118 insurgents have been killed trying to stop it.

The gun battles almost follow a pattern. Insurgents open fire from alleys, doorways and windows along al-Quds Street after creeping up on the US soldiers.

The soldiers return fire with heavy volleys of rifle, machinegun and cannon fire. Apache helicopters often finish it off with Hellfire rockets on the buildings where the gunmen are hiding.

Within minutes of the Hellfire missile, a thud sounds. It's the sound of another barrier section coming down.

"They (residents of the two neighbourhoods) are not ecstatic about it," said Capt. Todd Looney, commander of Charlie Company. "Unfortunately you can't make a barrier or an obstacle that only obstructs the movement of the insurgents.

"(But) even though they are inconvenienced in their daily movements around the city I think they understand. They may not appreciate it, they may not be happy about it, but I think they understand."

The wall is not the only US and Iraqi measure to cut JAM off from southern Sadr City. Independently and jointly the two militaries are engaging in hearts-and-minds outreach efforts.

The simplest are presence patrols in which soldiers move down streets, checking on security and meeting with local residents to establish personal relationships and a sense of security and trust.

Particularly successful are mobile medical clinics called MEDCAPS, in which Iraqi Army doctors with US and Iraqi troops providing security treat the ailments of all comers.

Special Civil Military Operations Centers have also been opened where people can meet with Iraqi government officials and US military personnel over issues such as sanitation, water supply, electricity, and even reparation payments for damage to property that occurred during operations against Shiite gunmen.

"I think the people here are scared of JAM (Jaish al-Mahdi) and the special groups and have had enough of this fighting," said Captain Ryan Williams, of Comanche Troop, 1st Squadron, 2nd Stryker Cavalry Regiment, which has outposts in the Tharwa neighbourhood.

"We've gotten a steady stream of tips on weapons caches and the hideouts and they've proved accurate." (dpa)