Iraqi Militants Use Chlorine in 3 Bombings

BAGHDAD, Feb. 21 — A truck bomb that combined explosives with chlorine gas blew up in southern Baghdad on Wednesday, and officials said it may represent a new and deadly tactic by insurgents against Iraqi civilians.

It was at least the third truck bomb in a month to employ chlorine, a greenish gas also used in World War I, which burns the skin and can be fatal after only a few concentrated breaths. The bomb killed at least two people and injured 32 others, police and medical officials said.

Iraqi and American officials said the use of chlorine seems aimed at bringing a new level of fear and havoc to Iraq as a new security plan for Baghdad takes shape.

Lt. Col. Christopher Garver, an American military spokesman, said the attacks highlighted the evolving fluidity of insurgent tactics in Iraq, dominated by militant groups who often notice and mimic attacks that attract the most attention and cause the most suffering.

Insurgents have shifted tactics to focus on helicopters, and on Wednesday one group forced down an American Black Hawk helicopter, the eight such incident since Jan. 20. Roadside bombs have been adapted to become deadlier, punching through heavily armored Humvees. Attacks on American soldiers also now include coordinated assaults from multiple locations, with a mix of weapons and in at least one case, counterfeit American uniforms and vehicles.

“The enemy is adaptive,” Colonel Garver said. “The enemy wants to win.”

The Black Hawk attacked on Wednesday was forced into a “hard landing” after taking fire from heavy machine guns and rocket-propelled grenades in Diyala Province, north of Baghdad, the United States military said. There were no injuries. A Sunni insurgent group, the Mujahedeen Army, claimed credit for the attack in an Internet posting, according to the SITE Institute, which tracks postings by insurgent groups.

The bombing involving chlorine gas on Wednesday followed an explosion on Tuesday north of Baghdad of a tanker filled with chlorine that had been rigged to explode, killing nine people and wounding 148, including 42 women and 52 children. At least one other attack with chlorine also took place on Jan. 28, according to the American military’s statements. Sixteen people were killed in that attack, in the Sunni-dominated Anbar Province, when a dump truck with explosives and a chlorine tank blew up in Ramadi.

The attacks seem to have been poorly executed, burning the chemical agent rather than dispersing it, but more sophisticated weapons involving chlorine could injure hundreds and cause mass panic.

Though it is widely used in water purification and sewage treatment, chlorine is dangerous because it reacts with water in moist tissue, such as eyes and the respiratory tract, to create acid, which essentially burns tissue. A few breaths of air containing chlorine at a thousand parts per million can be lethal.

Nine people were killed and 250 injured in 2005 after a train crash in South Carolina in which 60 tons of liquefied chlorine was released — about six times more than what is contained in a home heating fuel truck like the one used in the attack on Tuesday.

Exposures at far lower concentrations, down to two parts per million, cause coughing, shortness of breath, chest pain, burning in the throat, nose and eyes, nausea and swelling of the lungs.

A few hours after the attack, American Humvees and an American military vehicle with a nozzle that appeared to be testing the air encircled the scene. Soldiers were not wearing masks, but officials at Yarmouk hospital said they determined through interviews and tests that chlorine was the chemical used in the attack.

Brig. Qasim Atta, an Iraqi government spokesman for the new Baghdad security plan, described chlorine attacks as a “filthy way” to target vulnerable Iraqis, especially children.

Colonel Garver said that the chemical attacks could soon appear again. “Its no surprise that anti-Iraqi forces or terrorists or whoever is doing this are trying to replicate this kind of attack,” he said. “They perceive that it’s working.”

The attacks on Tuesday and Wednesday also indicated that the Baghdad security plan has pushed the violence beyond the city’s central neighborhoods, the focus of the new plan.

Maj. Gen. William B. Caldwell IV, a United States military spokesman in Baghdad, said that the “belt around Baghdad” had experienced an increase in attacks as Iraqi and American forces concentrate on neighborhoods within. At a briefing in the Green Zone, he said that top commanders were considering assigning at least one brigade to the ring around the city, and perhaps another to Diyala Province, which has been the site of vicious battles between Sunni insurgents and American and Iraqi troops.

The witnesses to the helicopter crash, also in Diyala Province, said that three helicopters, including a double-rotor Chinook, were flying at tree level, when gunmen began firing anti-aircraft machine guns from an area near an oil pipeline. A resident who would give his name only as Ali said the back of one helicopter burst into flame, leading the aircraft to turn sideways and plunge into the ground. Two other witnesses said they saw fire coming from the helicopter as it crashed around 1 p.m. local time.

Violence broke out on Wednesday in the southern Shiite holy city of Najaf, when a suicide car bomber detonated his payload as Iraqi security forces checked the car for weapons at a checkpoint into the center of city. The explosion occurred about a half a mile from the Imam Ali mosque, one of Shiite Islam’s holiest shrines, and killed at least 11 people, the police said. Another 34 were wounded.

The American military also said that a soldier was killed by gunfire in a northern neighborhood of Baghdad and that a marine died from combat in Anbar Province, where American troops have been battling Sunni insurgents for months. Both died Tuesday.

Meanwhile, despite the increased military effort, 20 bodies were found Wednesday in the capital, an Interior Ministry official said. In addition to the chlorine attack, four bombs ripped through areas of the city, killing at least six people, while mortar shells rained down on a Sunni neighborhood of western Baghdad, leaving three people dead.

The deadliest explosion occurred at about 5:30 p.m. local time, when an abandoned car exploded in Sadr City, the largest Shiite area of the capital, killing at least four people, witnesses said.

It was the second car bomb inside the neighborhood since the Iraqi government announced the start of the security plan one week ago. Two others have exploded at checkpoints on its edge.

Fatma al-Saiedi, 35, who was wounded in the explosion, said the attacks were a result of the new security plan, which has replaced the Mahdi Army, a Shiite militia, with what she and some other residents say are incompetent Iraqi policemen and soldiers.

“We trusted the Mahdi Army,” she said. “The Americans have arrested so many of them and now this happens — every day, another car bomb. We expect there to be more of them.”