U.S. soldiers are building a three-mile wall to protect a Sunni Arab enclave surrounded by Shiite neighborhoods in a Baghdad area "trapped in a spiral of sectarian violence and retaliation," the military said.

When the wall is finished, the minority Sunni community of Azamiyah, located on the eastern side of the Tigris River, will be completely gated, and traffic control points manned by Iraqi soldiers will provide the only means to enter it, the military said.

"Shiites are coming in and hitting Sunnis, and Sunnis are retaliating across the street," said Capt. Scott McLearn, of the U.S. 407th Brigade Support Battalion, which began the project April 10 and is working "almost nightly until the wall is complete," the statement said.

It said the concrete wall, including barriers as tall as 12 feet, "is one of the centerpieces of a new strategy by coalition and Iraqi forces to break the cycle of sectarian violence" in Baghdad.

U.S. and Iraqi forces have long erected barriers around city marketplaces and U.S. and Iraqi military facilities such as the heavily fortified Green Zone in Baghdad to prevent attacks, including homicide car bombs. But few, if any, have been known to be set up to divide a Baghdad neighborhood by sect.

The barrier will allow authorities to screen people entering and leaving Azamiyah in northern Baghdad "while keeping death squads and militia groups out." Such attacks can involve homicide bombers, death squads and militia snipers.

Security in the three Shiite communities on the other side of the wall also will be stepped up, and the barrier is expected to make it harder for insurgents to plant roadside bombs in the area targeting coalition forces, the statement said.

The construction work by the U.S. military involves flatbed trucks carrying concrete barriers weighing 14,000 pounds. Operating under bright lights, the cranes lift the barriers into place while being protected by U.S. tanks.

As work continued Friday, the day of worship in mostly Muslim Iraq, several Sunnis living in Azamiyah welcomed the effort to improve their security, but said the wall was another sign of the deep hostility between Sunnis and Shiites.

"It is good from one hand to curb violence and have control of terrorists. But it's bad on the other hand to be separated from others. We should live in one area like brothers, not be separated from one another," said Bashar Abdul Latif, a 45-year-old teacher.

"I don't think this wall will solve the city's serious security problems," said Ahmed Abdul-Sattar, 35, a government worker. "It will only increase the separation between our people, which has been made so much worse by the war."