US-backed Kurdish-led forces said on Monday that six of their fighters had been killed in a drone strike that came from areas of Syria's Deir Ezzor under the control of the Syrian regime.
Two local sources said the drone had come from an area where Iranian-backed proxies are active and regularly launch strikes. They said it had struck a military academy in Al Omar oil field that is located within a US base.
Iran-backed groups declaring support for the Palestinians have entered the fray across the region as the war between Israel and Hamas has intensified.
Hezbollah has fired at Israeli targets at the Lebanese-Israeli border, Iraqi militias have fired on US forces in Iraq and Syria, and the Houthis have fired on shipping in the Red Sea.