In 2019 the U.S. and Russia established rules of the air over Syria in order to avoid accidental and potentially provocative encounters. Both sides agreed that direct overflight of each other’s positions on the ground, particularly with armed aircraft, was not acceptable.

“The Russians have over the last several months seemed to abandon that tenet of the protocols,” Grynkewich said. The Russians still insist the U.S. stay away from Russian ground units, he explained, and the U.S. is adhering to that. But the Russians have even flown directly over U.S. troops on the ground in southern Syria, which he called provocative.

Grynkewich said the Russians could be taking a more aggressive posture to put pressure on the U.S. military presence in Syria, which they disagree with. But he said the fact that both the U.S. and Russia are supposed to be opposed to ISIS in Syria, and with the continuing — and in some cases growing — presence of ISIS in Syria, “it seems like a very strange time to do this.”

So far the overflights have not affected U.S. military operations on the ground, but the U.S. or coalition does respond to Russian aircraft, often shadowing them from afar. Grynkewich warned that if they had to respond to a Russian flight during a U.S. military operation on the ground, it could put the mission in jeopardy. 

“What it is really is a distraction from the fight against ISIS,” he said. “It hasn’t affected the fight on the ground yet, but it certainly has the potential to.”

“I’m not concerned about overt hostilities, I’m concerned about a miscalculation or unprofessional or immature action by somebody.”

“Over the course of my career I have not seen this kind of disregard for agreed upon protocols and deconfliction rules,” he said. “So this is very unique, what we’re seeing right now.”

The Russian Embassy in Washington, D.C., did not immediately respond to a request for comment.