U.S.-backed Kurdish-led forces said Monday that six of their fighters had been killed in an explosive drone attack by Iran-backed armed groups that came from areas of Syria's Deir al Zor under the control of the Syrian government.

Farhad Shami, a spokesperson for the Kurdish-led Syrian Democratic Forces (SDF), said in a post on X that the drone struck an SDF commando academy at a U.S. base at Al-Omar oilfield, resulting "in the martyrdom of six of our Commando fighters."

The Islamic Resistance in Iraq – an umbrella group of several Iran-backed Iraqi armed groups – on Monday claimed responsibility for a drone attack on Al-Omar field, saying it launched the attack Feb. 4.

Washington blames the group for a drone attack on a U.S. outpost in Jordan earlier this month that killed three U.S. forces. The U.S. launched dozens of strikes over the weekend against Iran-backed groups in Iraq and Syria, killing about 40 people, the vast majority reported to be militants.

Iran-backed groups declaring support for the Palestinians have entered the fray across the region as the war between Israel and the militant Hamas group has intensified.

Lebanese Hezbollah has fired at Israeli targets at the Lebanese-Israeli border, Iraqi militias have fired on U.S. forces in Iraq, Syria and Jordan, and the Houthis have fired on shipping in the Red Sea.