U.S. Troops in Iraq Face A Powerful New Weapon

Most such attacks have been carried out during the day and some have been videotaped and aired on the satellite television station operated by Hezbollah, a Lebanese militia and political movement. U.S. military officials said they have found Iranian-made 107mm rockets at some of the blast sites, which they said suggests the weapons -- or parts -- may have come from Iran.

The deadliest reported rocket-propelled bomb attack occurred June 4 in the Shaab neighborhood of eastern Baghdad. U.S. soldiers stationed at a small base called Forward Operating Base Callahan heard a series of blasts shortly after 2 p.m.

The explosions were caused when a rocket on the back of a small flatbed truck exploded, igniting the other four to five IRAMs on the truck, the U.S. military said. The attack killed 18 Iraqis, wounded 29 and damaged 15 buildings, the military said.

"It is believed that the intended targets were U.S. soldiers at FOB Callahan and while in the final stages for the attack, for an unknown reason one rocket prematurely detonated causing the remaining rockets to explode erratically," the military said in a statement.

U.S. military officials said two suspected assailants were killed in the attack, describing them as members of "special groups" or Iranian-backed Shiite militias.

The second-deadliest attack occurred April 28 at Forward Operating Base Loyalty in eastern Baghdad. The attack, which took place shortly after 1 p.m., killed three soldiers. Militiamen fired 14 rocket-propelled bombs from the back of a cargo truck.

That same day, Joint Security Station Thawra, the U.S. military's only outpost in Sadr City, in eastern Baghdad, was also attacked with rocket-propelled bombs.

A man walked into an office at the station where Iraqis can file claims for compensation, and told soldiers of a U.S. military civil affairs unit that his truck had sustained damage during recent clashes between American troops and militiamen, according to two U.S. military officials who described the attack, speaking on the condition of anonymity because the information has not been publicly released.

The soldiers told the man to drive his truck close to the station so they could inspect it. The man pulled up in a small delivery truck containing eight IRAM launch tubes. The station was attacked soon afterward. At least 15 soldiers were wounded.

Although most rocket-propelled bomb attacks have taken place in eastern Baghdad, a joint security station in northern Hurriya, western Baghdad, was targeted last month.

On June 24, at approximately 3 p.m., a man walked up to the gate of the base and told soldiers, "You have a truck over there that goes boom," according to Capt. Jeremy Ussery, a company commander with the 101st Airborne Division's 1st Battalion, 502nd Infantry Regiment.

When soldiers inspected the truck, they realized an attempt to ignite nine IRAMs, with roughly 200 pounds of explosives apiece, had been unsuccessful.

"Just think of what could have happened," Ussery said. "Eighteen hundred pounds of explosives dispersed over this JSS."

The battalion approved a $50,000 reward for information on the attack and soldiers have handed out fliers to residents seeking tips. Ussery said the battalion typically offers rewards in the $10,000 range for "high value individuals," or prominent wanted militiamen.

The amount offered for information on the IRAM attack "is a very large reward," he said. "It's a small price to pay."

Staff writer Josh White contributed to this report from Washington.