The terrorist PKK group's Syrian offshoot YPG shot a U.S. MQ-9 Reaper drone in northern Syria, a report said Wednesday.

CNN reported, citing multiple officials familiar with the matter, that SDF forces believed the multimillion-dollar drone was Turkish when the group downed the aircraft Monday.

An American defense official told Anadolu Agency (AA) earlier that the U.S. Air Force lost contact with an unmanned MQ-9 Reaper operating above Syria in support of Operation Inherent Resolve on Dec. 9.

"We are actively assessing the incident to determine the cause and follow-on actions," the official said in a statement.

Northern Syria has recently seen the advance of Syrian opposition groups to liberate areas forcibly seized by the YPG/PKK terror group.

The MQ-9 is a drone operated by the U.S. Air Force, capable of performing surveillance missions and offensive strikes.

Nearly 900 U.S. military personnel are stationed in Syria as part of an anti-Daesh coalition that includes the SDF.

The SDF is the U.S.' primary anti-Daesh partner in Syria. The group is led by the YPG, the Syrian offshoot of the PKK, a designated terror group in the U.S. and Türkiye. Washington's support for the SDF has greatly exacerbated tensions between the two NATO allies.