The U.S. military carried out multiple air strikes in Syria on Thursday night against Iran-aligned groups who it blamed for a deadly drone attack that killed a contractor, injured another, and wounded five U.S. troops, the Pentagon said.

The strikes were in retaliation for an attack against a US-led coalition base near Hasakah in northeast Syria at approximately 1:38 p.m. (1038 GMT) on Thursday, it said.

The U.S. intelligence community assessed that the drone was Iranian in origin, the military said.

U.S. Defense Secretary Lloyd Austin said the strikes targeted groups affiliated with Iran’s Islamic Revolutionary Guards Corps.

“The airstrikes 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,” Austin said in a statement.