U.S. military hits a wall in Iraqi militia stronghold

For Boyes' team, each attempt to add to the wall, which is designed to run the 3-mile length of Route Gold, is a combat mission. But the military has made it clear it won't cross the road, whose formal name is Al Quds Street, even as the Pentagon stepped up accusations that Iranian-backed fighters were using the area beyond as a base to launch attacks that have killed scores of U.S. and Iraqi forces and civilians in the last month. U.S. and Iraqi officials say they have uncovered evidence of Iranian involvement in training and supplying fighters in Shiite militia strongholds.

"There's always a danger in giving an insurgent force a safe haven, but you always have to look at the strategic consequences," Army Lt. Col. Mike Pappal said.

By building the wall, which will be about 12 feet high, Pappal said, the military will protect people on its side of Route Gold and limit escape routes for insurgents. It also will push back the Shiite fighters who launch mortar rounds and rockets at the Green Zone, which includes the U.S. Embassy and most Iraqi government offices. From the far side of Route Gold, it will be much more difficult for them to hit their targets.

Once the wall is completed, the military says, it plans to lavish streetlights on the neighborhoods it occupies and install other improvements in hopes of encouraging residents to reject extremism. Construction began April 15, but it will not be completed for several more weeks in part because of the delays caused by combat.

The United States' predicament is a sign of Sadr's status as a political power broker. He controls 30 seats in parliament, and his weekly messages read out in mosques across Iraq have a huge effect on violence in Sadr City and other Shiite neighborhoods of Baghdad.

"When he says stop shooting, they do as he says," Boyes said, citing Sadr's March 30 call to halt violence. It brought an immediate end to the shower of rockets and mortar shells that had been pummeling the Green Zone. Rocket fire resumed two weeks later and has remained relatively consistent since Sadr rejected Prime Minister Nouri Maliki's demands that he disarm the Mahdi Army militia.

The streets surrounding Boyes' base, a former butcher shop, were prime rocket-launching terrain before the troops moved in. Sandbags and concrete walls surround the structure. Cots cover virtually every inch of the floor inside except for makeshift footpaths. More cots are outside beneath the trees. Day and night, most are occupied by troops sleeping, reading or watching movies on their laptops.