The Mehdi Army has been trying, but failing, to prevent its progress:
The Mahdi Army is desperately trying to stop the barrier from being built, and is focusing its attacks on US engineers and patrols as they work to complete it. The Mahdi Army has launched complex attacks and ambushes using small-arms, machine guns, rocket-propelled grenades, and roadside bombs.
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These attacks have not stopped the barrier from being built, said Stover, who visited the construction sites on Qods Street on May 1. “As the engineers were emplacing the barriers an M1A1 Abrams fired a main gun round at militants across the street,†Stover said. “We fired 5 Hellfire missiles and dropped two JDAMs from fixed wing aircraft. It got a bit hot today, but our Soldiers continued emplacing the barriers.â€
The wall should help bottle up the militia in the northern part of Sadr City, allowing the government to establish services and security in the southern neighborhoods.
Meanwhile, Maliki’s government sent an envoy to Iran with “sufficient evidence” that Iran is fomenting violence and arming Shia militias, to demand that they cut it out posthaste. It’ll be fun seeing how those claiming Maliki is pro-Iran spin this inconvenient fact. Looks the strategy du jour is to ignore it and hope no one notices that Maliki is not only seizing huge quantities of Iranian weapons from the militias armed by his supposed close allies, but is also demanding those alleged allies stop interfering in his country, while killing hundreds of their proxies.

