The strike took out at least 12 Iranian-backed fighters, destroying vehicles and weapons depots.
A minimum of 12 militiamen who fought with the backing of Iran were slain in airstrikes on their base in Syria on Saturday, according to the Syrian Observatory for Human Rights (SOHR) watchdog group.
The SOHR said that unidentified drones hit an Iranian militia base in eastern Deir Ezzor around midnight.
The fighters were reportedly Iraqi and Afghani nationals.