April 5 (UPI) -- The Pentagon has revised the estimate on the number of U.S. troops in Iraq killed by Iranian-backed militias to 603, from roughly 500, between 2003 and 2011.
During a State Department briefing Tuesday, Special Representative for Iran Brian Hook said the revised figures are taken from recently declassified U.S. military documents. The original estimate came from Chairman of the Joint Chiefs of Staff General Joseph Dunford in 2015.
"We were not always able to attribute the casualties that we had to Iranian activity, although many times we suspected it was Iranian activity, even though we did not necessarily have the forensics to support that," Dunford told Congress during a confirmation hearing.
Islamic Revolutionary Guard Corps, which is Iran's elite military force that protects the regime from internal and external threats, is responsible for 17 percent of all U.S. service personnel deaths in Iraq. Iran supplied weaponry to Shiite militias fighting U.S. occupation.
"These casualties were the result of explosively formed penetrators, other improvised explosive devices, improvised rocket-assisted munitions, rockets, mortars, rocket-propelled grenades, small-arms, sniper, and other attacks in Iraq," Navy Cmdr. Sean Robertson, a Pentagon spokesman, told Military Times.
In addition, "thousands" of Iraqi troops and civilians were killed in attacks by Iranian proxy forces, according to Hook.
Hook told reporters the United States continues to pressure Iran with sanctions.
"We are imposing costs on the regime for behaving as an outlaw expansionist regime," he said. "The regime is weaker today than when we took office two years ago. Its proxies are also weaker. Unless the regime demonstrates a change in policy and behavior, the financial challenges facing Tehran will mount."