Three US service members killed in Jordan by Iran-backed forces

This story was updated at 11 p.m. Eastern.

Three U.S. service members were killed and up to 34 injured in Jordan, near the Syrian border, by one-way attack drones fired by Iran-backed forces in Iraq, U.S. Central Command, or CENTCOM, said in a series of statements Sunday. 

“While we are still gathering the facts of this attack, we know it was carried out by radical Iran-backed militant groups operating in Syria and Iraq,” the White House said in its own Sunday statement.

The attack targeted a Jordanian logistics support base. "There are approximately 350 U.S. Army and Air Force personnel deployed to the base, conducting a number of key support functions, including support to the coalition for the lasting defeat of ISIS," CENTCOM said in a later statement. 

Defense Secretary Lloyd Austin, in a statement, said he was "outraged and deeply saddened by the deaths of our three U.S. service members and the wounding of other American troops...who were deployed to a site in northeastern Jordan near the Syrian border to work for the lasting defeat of ISIS." 

Austin also said "Iran-backed militias" are behind the attacks, adding that the United States "will respond at a time and place of our choosing." 

The Islamic Resistance in Iraq, an Iran-backed group that includes several smaller groups such as Kataib Hezbollah, took responsibility, according to the Washington Post.

The attack came days after U.S. forces took action against three Kataib Hezbollah facilities in Iraq. 

“These strikes targeted KH headquarters, storage, and training locations for rocket, missile, and one-way attack UAV capabilities,” CENTCOM said in a statement Tuesday. 

That strike was a response to missile and drone attacks on U.S. troops in the region, including a multi-missile attack against ​​al-Assad Airbase in western Iraq that injured several service members. 

There have been 165 attacks on U.S. troops in the region since mid-October, 66 in Iraq and 98 in Syria.

“We will carry on their commitment to fight terrorism. And have no doub—we will hold all those responsible to account at a time and in a manner of our choosing,” the White House said. 

Charles Lister, a senior fellow and the director of the Syria and Countering Terrorism and Extremism programs at the Middle East Institute, called the attack a “huge escalation, and what everyone’s worried about since the first attack on October 18.” 

John Spencer, chair of urban warfare studies at the Modern War Insitute at West Point, said the U.S. response “will be complex but if not overwhelming to all responsible, a significant blow to U.S. national security interests. Containment of the Iranian regime has not worked.”

Speaker of the House Rep. Mike Johnson, R-La., said, “America must send a crystal clear message across the globe that attacks on our troops will not be tolerated.”