Suicide Bombing Kills 12 in Baghdad

An injured Iraqi man lies at a hospital after a suicide car bomber crashed into an Iraqi police checkpoint, killing 33 and injuring 75 at an entrance to Sadr City, the capital's biggest Shiite Muslim neighborhood, in Baghdad, Iraq, Wednesday, April 18, 2007. Four large bombs exploded in mostly Shiite areas of Baghdad on Wednesday, killing at least 164 people and wounding scores _ the deadliest day in the city since the start of the U.S.-Iraqi campaign to pacify the capital. (AP Photo/Ali Abed) (Ali Abed - AP)

Despite new barricades and checkpoints erected as part of the security crackdown, a fraction of the cars in Baghdad _ a city of 6 million residents _ are searched at all. Many of the suicide car bombs explode at the checkpoints, either targeting Iraqi troops or detonating a moment before they are discovered.

Some local media have suggested that Sunni insurgents have secretly stockpiled explosives in Shiite areas, and are now rigging their cars with bombs very close to their targets to avoid driving long distances and risking security checks.

Lt. Col. Christopher Garver, a U.S. military spokesman, told The Associated Press the American military strategy was two-pronged: raiding car-bomb factories on the outskirts of Baghdad, and clearing weapons stashes hidden in dense urban areas inside the capital.

"We want to close down access to the city, but we also want to be inside these neighborhoods to find these caches of explosives. If the final assembly exists inside the city, that's what our clearing operations will be targeting," he said.

But he said the strategy would not be fully implemented until June 1.

"We don't have all the troops for the surge _ we're only at three of five brigades so far. It's not fully in place," Garver said. "Still, I can't say if we had those two brigades, yesterday wouldn't have happened. This enemy is adaptive."

Thursday's bombing hit hours before U.S. Defense Secretary Robert Gates arrived on an unannounced visit to warn Iraqi leaders that the U.S. commitment to a military buildup there is not open-ended.

Gates said the political tumult in Washington over financing the war shows that both the American public and the Bush administration are running out of patience.

"I'm sympathetic with some of the challenges that they face," Gates said of the Iraqis. But, he said, "the clock is ticking."

Al-Maliki, the prime minister, said militants had "proven their spite by targeting humanity."

"It is an open battle and it will not be the last in the war we are fighting for the sake of the nation, dignity, honor and the people," he said at a ceremony marking the 50th anniversary of the founding his Islamic Dawa Party.

"This is Iraq. They sabotage and we build and continue the reconstruction," al-Maliki said defiantly.