"Four missiles fell on the territory of a US base in Koniko," a source said.
The missile strike on the Koniko gas field in the Syrian province of Deir ez-Zor was followed by a drone attack on a US installation in the Omar oil field in the same province, another source said.
"Three drones attacked an American base. Several explosions were heard at the base," the source said, adding US air defenses failed to foil the attack.
These are the latest in a string of more than 160 attacks on US facilities in Syria and neighboring Iraq that Washington attributes to Iran-backed militias. The Pentagon retaliated last week by striking targets belonging to militant groups who it says killed three US troops in an attack on a US outpost near Jordan in early February. Iraq and Syria condemned the US aggression against their territories.