The Pentagon is upping the official estimate on the number of U.S. troops in Iraq who were killed by Iranian-backed militias, now putting that number at at least 608.

Officials previously said that Iran was linked to the deaths of roughly 500 troops.

That means roughly one in every six American combat fatalities in Iraq were attributable to Iran.

The deaths are attributed to proxies sponsored by the Islamic Revolutionary Guard Corps — Iran’s elite military force that protects the regime from internal and external threats.

“I can announce today, based on declassified U.S. military reports, that Iran is responsible for the deaths of at least 608 American service members,” State Department deputy spokesman Robert Palladino said during a press brief Tuesday. “This death toll is in addition to the many thousands of Iraqis killed by the IRGC’s proxies.”

That new total accounts for 17 percent of all deaths of U.S. personnel in Iraq from 2003 to 2011, the State Department said.

“That’s a Department of Defense statistic," Palladino added.

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Most of the deaths occurred during the surge in Iraq, when President George W. Bush pushed thousands more troops into the country to deal with the sectarian civil war boiling over between Shiite and Sunni groups.

American personnel in Iraq faced off against highly lethal bombs, known as explosively formed penetrators, or EFPs, which were allegedly manufactured and supplied by Iran to Shiite militias across the border in Iraq.

Lawsuits filed in U.S. District Court in Washington have previously attempted to hold the Iranian government legally accountable for the deaths of Americans that died from these weapon systems.