Insurgents in Iraq seen shifting focus

He said security was being increased around hospitals and government buildings, and he called on schools to put up checkpoints and keep cars off their campuses.

Assailants have previously bombed civilian targets, including the Baghdad headquarters of the United Nations and the International Committee of the Red Cross. Both organizations pulled most of their foreign staff out of Iraq after those deadly attacks.

In a city where sandbagged checkpoints, cement barriers, and armed guards protect many potential targets, the Nabil Restaurant was easy prey.

Situated on a busy street, it was protected by just one armed guard and had no cement barriers or sandbags to shield wealthy patrons from the blast of the car bomb, which detonated Wednesday night as Iraqis and Westerners celebrated.

Colonel Ralph Baker, commander of the Second Brigade of the First Armored Division, said the blast was caused by a car booby-trapped with about 500 pounds of explosives. He said reports that it was a suicide bomb attack were false, and that witnesses said they saw a man running from a vehicle before the explosion.

No group has claimed responsibility for the bombing, but Baker said the US military and Iraqi police were following up leads.