Russian fighter jets were captured on video harassing US military drones above Syria. The US Air Force said the MQ-9 Reaper drones were conducting a mission against ISIS Wednesday. US officials have warned that Russian aircraft are increasingly carrying out aggressive actions

Several Russian fighter jets bullied a trio of US military MQ-9 Reaper drones operating above Syria on Wednesday, the US Air Force said, marking the latest provocation by Moscow's aircraft in the region.

The Reaper drones were conducting a mission against Islamic State targets on Wednesday morning when three Russian Su-35 jets closed in on the aircraft and began engaging in "unsafe and unprofessional behavior," Lt. Gen. Alexus Grynkewich, the commander of US Air Forces Central Command (AFCENT), said in a statement.

Grynkewich said the Russian pilots harassed the drones on multiple occasions during the engagement.

"Against established norms and protocols, the Russian jets dropped multiple parachute flares in front of the drones, forcing our aircraft to conduct evasive manoeuvres," he said. "Additionally, one Russian pilot positioned their aircraft in front of an MQ-9 and engaged afterburner, thereby reducing the operator's ability to safely operate the aircraft."

An unclassified video published by the Air Force shows some moments of the engagement. In one frame, a Su-35 can be seen closing in on one of the MQ-9s, and later on, the parachute flares are captured falling through the drones' flight path. At one point, the caption slams the engagement as a "new level" of inappropriate action by Russia's air force over Syria.

"These events represent another example of unprofessional and unsafe actions by Russian air forces operating in Syria, which threaten the safety of both US and Russian forces," Grynkewich said. "We urge Russian forces in Syria to cease this reckless behavior and adhere to the standards of behavior expected of a professional air force so we can resume our focus on the enduring defeat of ISIS."

US officials in recent months have called attention to increasingly aggressive manoeuvres by Russian pilots in close proximity to American interests and assets across the Middle East, like armed flyovers of military positions and signalling a desire to dogfight.

To counter this phenomenon, US Central Command (CENTCOM) announced in June that it deployed a squadron of F-22 Raptors to the Middle East in a show of strength against Moscow. A US Air Force official told Insider at the time that although the jets will send a message, their main mission is to contribute to the ongoing campaign against the Islamic State.

Russia's "regular violation of agreed upon airspace deconfliction measures increases the risk of escalation or miscalculation," Gen. Michael Kurilla, CENTCOM commander, said in response to Wednesday's harassment.

Although the Reaper drones were not damaged, such an incident would not be unprecedented; a pair of Russian Su-27 fighters in March dumped fuel on and flew in front of a US military MQ-9 that was operating above the Black Sea before one of the jets clipped the drone, forcing Washington to bring it down into international waters.

(With Inputs From International Agencies)