Three drones were aimed at a US base in Syria's Al Tanf region on Friday, the American military has said. No US troops were injured.
The US Central Command (Centcom) said two of the drones were shot down while the third hit the compound, injuring two members of the Washington-backed Syrian Free Army forces.
"This morning, three one-way attack drones attacked the Al Tanf Garrison in Syria," the Army said.
"Two of the drones were shot down by Coalition Forces while one struck the compound, injuring two members of the Syrian Free Army partner force, who received medical treatment."
Centcom spokesman Joe Buccino condemned the assault.
“Attacks of this kind are unacceptable – they place our troops and our partners at risk and jeopardise the fight against ISIS,” he said .
No group claimed responsibility for the attack.
In November, two rockets were aimed at a US military patrol base in north-eastern Syria amid heightened tensions in the region following Turkey's attacks targeting Kurdish groups.
Centcom said the rocket attack on the base in Al Shaddadi, about 100km from the Turkey-Syria border, did not cause any injuries or damage.
