The U.S. military launched multiple precision airstrikes against targets in Syria on Thursday after an attack using an Iranian drone killed an American contractor and wounded six others, including five U.S. soldiers.

Defense Secretary Lloyd Austin said the retaliatory strikes targeted Syrian militias linked to Iran’s Islamic Revolutionary Guard Corps (IRGC).

“The air strikes were conducted in response to today’s attack as well as a series of recent attacks against Coalition forces in Syria by groups affiliated with the IRGC. No group will strike our troops with impunity,” Austin said.

“This evening, we responded to an attack on our forces that killed an American contractor and wounded our troops and another American contractor by striking facilities used by groups affiliated with Iran’s Islamic Revolutionary Guard Corps. This was another in a series of attacks on our troops and partner forces,” said Gen. Michael Kurilla, head of U.S. Central Command (CENTCOM).

Around 6000 Iranians from the diaspora demonstrate in the streets of Brussels on February 20, 2023, in Brussels, Belgium. Waving Iranian but also European flags, they demand that the Islamic Revolutionary Guard Corps (IRGC) organization be classified as terrorist. (Thierry Monasse/Getty Images)

“The thoughts and prayers of U.S. Central Command are with the Family of our contractor killed and with our wounded servicemembers and contractor,” Kurilla added.

The London-based Syrian Observatory for Human Rights (SOHR) said at least eight pro-Iranian fighters were killed in the U.S. airstrikes, one of which hit an arms depot in the city of Deir el-Zour, while the other targeted a militia outpost near the town of Mayadeen. 

SOHR’s sources said there was a third American airstrike on a militia post near the Iraqi border that may have killed another three IRGC-backed Syrian fighters, but that report was of lower confidence as of Friday morning.

Iranian state media claimed no Iranians were killed in the U.S. strikes and said they targeted a civilian “rural development center” and “grain facility” rather than militia bases.

Iran’s state-run PressTV quoted a “military source in Syria” who said the IRGC-backed militias “reserve their right to respond to the American attack and will take reciprocal action.” 

A pro-Iranian television network in Lebanon claimed the militias targeted an American base near the al-Omar oil field in northeastern Syria with a retaliatory missile attack after the U.S. airstrikes were conducted. Al-Omar is Syria’s largest oil field. The Lebanese TV report had not been corroborated as of Friday morning.

In this Monday, Dec. 23, 2019, photo, a U.S. soldier carries Christmas gifts from a helicopter to deliver to his comrades on a base near the al-Omar oilfield in eastern Syria. (Farid Abdul-Wahid/AP)

The U.S. base at the oil field has been targeted by rocket attacks from Iran-backed terrorist groups in the past. Kurilla said U.S. forces at various locations in Syria have been attacked by Iran-backed militants 78 times since 2021. Fatalities in these attacks have been uncommon until now.

The incident that prompted Thursday evening’s U.S. airstrikes occurred early Thursday afternoon, when an unmanned aerial vehicle (UAV) crashed into a building at the U.S.-led coalition base in the northeastern Syrian city of Hassakeh. According to Austin, U.S. intelligence quickly assessed the UAV was of Iranian origin, and President Joe Biden ordered a military response against Iranian client groups in Syria.

The Pentagon said two of the U.S. troops injured by the Iranian drone attack were treated at the base in Hassakeh, while the other three wounded troops and the injured contractor were evacuated to a medical facility in Iraq.

Kurilla told the House Armed Services Committee on Thursday that Iran’s military is “exponentially more militarily capable than it was even five years ago.” He cited the drones Iran is providing to its Syrian proxy forces as a major factor in that growing offensive capability.

“The Iranian regime now holds the largest and most capable unmanned aerial vehicle force in the region,” the CENTCOM commander said.