Tehran claimed Monday that an American reconnaissance drone based in Afghanistan turned away before crossing into Iranian airspace, after it was warned off by a defense base over the border.

According to a report in the semi-official Fars news agency, the drone “was dissuaded from accomplishing its mission after Khatam ol-Anbia Air Defense Base gave it a serious warning.”

The report said the “radar-evading” drone took off from a base in Kandahar and came within 32 kilometers (20 miles) of the Iranian border when the warning was issued. Fars did not specify how the warning was communicated to the unmanned aerial vehicle.

There was no immediate confirmation of the incident from the US military.

It comes as leaders in Tehran have been making threatening statements about fending off American “aggression,” and following an incident in which Iranian gunships chased an American warship. The US military said the ship was “harassed” while in international waters.

In 2014, Iran said it had successfully tested its own version of a US-made drone based on one it had captured.

Iran has said it managed to reverse-engineer the RQ-170 Sentinel, seized in December 2011 after it entered Iranian airspace from neighboring Afghanistan, and that it is capable of launching its own production line for the unmanned aircraft.

Iran says it has captured several American drones in recent years, including a Boeing-designed ScanEagle drone — a less sophisticated aircraft — after it entered Iranian airspace over the Persian Gulf. Tehran says it is also copying the ScanEagle and plans to put its version into service.

AFP contributed to this report.