President Joe Biden ordered the U.S. military to carry out retaliatory strikes against Iranian-backed militia groups after three U.S. servicemembers were injured in a drone attack in northern Iraq.

National Security Council spokeswoman Adrienne Watson said one of the U.S. troops suffered critical injuries in the attack that occurred earlier Monday. The Iranian-backed militia Kataib Hezbollah and affiliated groups, under an umbrella of Iranian-backed militants, claimed credit for the attack that utilized a one-way attack drone

Biden, who is spending Christmas at the presidential retreat at Camp David, Maryland, was alerted about the attack by White House national security adviser Jake Sullivan shortly after it occurred on Monday and ordered the Pentagon and his top national security aides to prepare response options.