Iraq Insurgents Again Use 'Dirty' Attack

A man injured in a suicide bomber attack lies in Baghdad's al-Kindi hospital, Iraq, Wednesday, Feb. 21, 2007. A suicide bomber struck a funeral in Baghdad on Tuesday, killing at least seven people and injuring another 15, as militants show increasing defiance to a major security operation in the capital. (AP Photo/Karim Kadim) (Karim Kadim - AP)

Some authorities believe militants could be trying to maximize the panic from their attacks by adding chlorine or other noxious substances.

"It is an indication of maliciousness, a desire to injure and kill innocent people in the vicinity," said Garver, who also predicted militants may begin to launch similar attacks because of the widespread mayhem caused by this week's chlorine clouds.

"If there is a particular success, we'll see copycats. ... They certainly pay attention to what they think is successful," he said.

In Najaf, meanwhile, a suicide car bomber killed at least 13 at a police checkpoint. The attack fit a pattern that's believed to drive much of Iraq's recent violence: Sunni militants seeking to provoke majority Shiites into a full-blown sectarian conflict that would leave Washington's plans in ruins.

It was the first major bombing in more than six months in Najaf, an important Shiite pilgrimage site 100 miles south of Baghdad and also the headquarters of radical Shiite cleric Muqtada al-Sadr, head of the Mahdi Army militia.

The Najaf blast hit while streets were filled with morning shoppers. At least seven of the victims were police and the rest civilians near a checkpoint _ part of the city's security cordon that includes Mahdi Army militiamen, who battled U.S. forces in the area in 2004.

More than 40 people were wounded in the blast, which sent body parts and blood over a wide boulevard. Crews stuffed limbs and bits of flesh into cardboard boxes.

In Baghdad, another Mahdi Army center was hit. A car bombing in the teeming Sadr City district killed at least three.

More than 10 people died in blasts across Baghdad _ adding to the more than 100 victims of bombings in attacks in and around the capital since Sunday. The toll cast a long shadow over authorities marking the first week of the U.S.-Iraqi security sweeps.

Moussawi, the Iraqi military spokesman, said the campaign to reclaim control of the city "has achieved very important goals despite the expected criminal reactions."

"God willing, the plan will continue to uproot terrorists and outlaws across Baghdad and other areas," he told a news conference. He added that 42 "terrorists" have been killed in the sweeps and more than 250 suspected militants arrested, but gave further details.

An American military spokesman, Maj. Gen. William Caldwell, told a news conference that U.S. and Iraqi forces were focusing on "belts" of extremist activity in Baghdad and suggested talks are ongoing over when and how to move into Sadr City.