A Russian fighter jet flew «dangerously close» to a US hunter-killer drone over Syria on Sunday and released a flare that caused severe damage to the drone’s propeller, the US Air Force said on Tuesday.

At 12:23 a.m. ET Sunday, the Russian plane came within a few feet of the MQ-9 Reaper drone, which was on a mission to «defeat ISIS,» said Air Force Lt. Gen. Alex Grynkewich, commander of the Ninth Air Force and Combined Forces Air Component for U.S. Central Command.

«The Russian fighter’s blatant disregard for flight safety detracts from our mission to ensure the lasting defeat of ISIS,» he said, referring to the Islamic State terror group.

The damaged propeller of the American drone. US Air Force via AP

«We call on the Russian forces in Syria to immediately stop this reckless, unprovoked and unprofessional behaviour.»

The Russian Defense Ministry did not immediately respond to requests for comment.

It is at least the third such incident this month, following similar collisions between Russian planes and US drones over Syria on July 5-6.

The Air Force released a video that it said showed the Russian plane flying close to the drone and releasing a flare.

The crew operating the MQ-9 drone were able to fly it to their home base, it added. The drone has a wingspan of 66 feet and costs $56.5 million at 2011 prices, according to the Air Force website. It can carry Hellfire missiles and precision-guided bombs.

An MQ-9 Reaper drone flying over Nevada in 2007.
An MQ-9 Reaper drone flying over Nevada in 2007. Ethan Miller / AFP – File Getty Images

Russia has used its air power to support Bashar al-Assad’s regime during Syria’s long-running civil war, with deadly airstrikes on rebel-held territory.

In March, Grynkewich told NBC News that armed Russian planes flew over US positions in Syria almost every day.