The US military shot down a small drone, which it said had penetrated the al-Tanf base in southern Syria, weeks after the base itself was attacked by a drone and rockets.
NBC News quoted a spokesman for the US Central Command, Bill Urban, as saying that the army detected two drones entering the airspace around the Al-Tanf base - which is located in southern Syria near the borders with Iraq and Jordan - on Tuesday evening.
Orben added that one of the two drones penetrated the area, and the US forces considered it a hostile target and shot it down, without causing any losses or damage to the base.
The second drone left the area, and it was not clear if either of the two drones was carrying explosive materials.
This incident comes weeks after a coordinated attack on the Al-Tanf base on October 20, in which a group of drones participated, some of which were loaded with explosives, followed by rocket-propelled grenades, according to the US military.
US military officials said that the attack did not cause any deaths or injuries among the US forces stationed there, but it caused great damage to the facilities.
The officials added that Iran or Iran-backed armed factions are suspected of being behind the coordinated attack, as well as the drone incident last Tuesday.
Al-Tanf base is located on a vital route for Iranian-backed forces, as it extends from Tehran through Iraq and Syria to southern Lebanon and the Israeli border.
The New York Times earlier quoted US and Israeli officials as saying that the attack on the Al-Tanf base last October was an Iranian response to an Israeli raid in Syria.
A senior US military official told the newspaper that two of the five drones exploded and were loaded with explosive devices, and that the aim of the raid was to kill, but there were no injuries.