The United States is showering targets in Iraq with the most unpredictable weapons in its arsenal: tiny cluster bombs so deadly they can demolish a tank, but so erratic they can take years to blow up.
The U.S. Central Command in Doha, Qatar, said it is investigating reports that cluster bombs killed at least 11 civilians in Hillah, a city 60 miles south of Baghdad and the scene of heavy fighting.
The military acknowledged for the first time Wednesday that cluster bombs were being deployed. Human rights groups have called for their ban, and their use during the campaign to oust Saddam Hussein is particularly sensitive because of the stated aim of the U.S.-led force to minimize civilian casualties.
"Cluster bombs have a very bad reputation, which they deserve," said Colin King, author of Jane's Explosive Ordnance Disposal guide and a British Army bomb disposal expert from the 1991 Persian Gulf War.
A Central Command spokesman, Navy Capt. Frank Thorp, said the munitions are playing a tactical role in the battlefield and work well against large targets, such as an airfield. "It's a very effective weapon," he said.
While protecting civilians is important, he said, "let's be very clear, weapons are designed for war. There is no weapon that doesn't cause harm except for the leaflets we have been dropping for the past month."
In Baghdad, Iraqi Health Minister Omid Medhat Mubarak accused U.S. and British forces were targeting civilians with cluster bombs. "In Najaf, they destroyed a medical center," he said. "They bombed an ambulance and killed its driver."
The U.S. command has denied targeting civilians.
A single cluster bomb can scatter hundreds of tiny bomblets over an area the size of a football field. These bomblets can be packed in rocket-fired artillery shells or dropped while housed in a shell that looks like a regular bomb, but opens to release scores of parachute-borne bomblets.
Mortar rounds, artillery shells and cluster bombs generally have a dud rate of about 10-25 percent, King said. But critics denounce the use of cluster bombs because of their sheer numbers - more than 50 million bomblets were dropped during the 1991 Persian Gulf War - and the danger the duds pose to civilians and friendly troops.
Human Rights Watch noted that two U.S. Marines were killed - one on Sunday and the other the next day - after stepping on unexploded cluster bombs. In 1991, six U.S. Army combat engineers were killed while disposing of cluster bombs.
Also during the previous Gulf war, one soldier looking for war souvenirs lost a leg in the Iraqi desert when he stuffed a cluster bomb into his pocket. Members of his First Cavalry Division ran to their vehicles, believing the blast was incoming gunfire, and a second soldier died when he stepped on another canister.
Cluster bombs are quickly catching up to landmines as the lethal legacy of an old war. Human Rights Watch said ordnance experts in Kuwait, which was heavily bombed after Iraq claimed the country as its own in 1991, were finding roughly 200 cluster bombs per month just last year - roughly the same rate as the previous year.
Countries generally rely on private contractors to scoop up mines and dud bombs in war zones. Because of the nature of modern warfare, business is booming.