The Syrian government claims to have shot down a US drone that was flying near the western city of Latakia.
Washington confirmed it lost contact with a reconnaissance aircraft in the region but didn't say whether it was downed or it crashed in an accident.
"US military controllers lost contact with an US MQ-1 Predator unarmed remotely piloted aircraft operating over northwest Syria," said Pentagon spokeswoman Navy Cdr. Elissa Smith, USA Today reported.
MQ-1 Predator drones are used for intelligence gathering operations in the US led aerial campaign against the Islamic State (Isis) in Syria and Iraq.
If confirmed, the downing will be the first of a US aircraft in the region since the anti-IS offensive was launched in September last year.
Syrian president Bashar al-Assad claimed in a February interview with the BBC that US forces shared some general information about the airstrikes with the Syrian military as part of a loose coordination effort against the Islamist group.
Syria's state television showed close-ups of a wheel and other parts of the downed drone, as well as military officials loading what were said to be debris of the aircraft into a truck.
In December the regime similarly claimed it captured an Israeli Skylark I model UAV drone that was flying over the province of Quneitra, near the Israeli-occupied Golan Heights.