WASHINGTON — A Russian fighter jet flew within a few meters of a U.S. drone over Syria and fired flares at it, striking the American aircraft and damaging it, the U.S. military said Tuesday, the latest in a string of aggressive intercepts by Russia in the region.

A senior Air Force commander said the move on Sunday was an attempt by the Russians to knock the MQ-9 Reaper drone out of the sky and came just a week after a Russian fighter jet flew dangerously close to a U.S. surveillance aircraft carrying a crew in the region, jeopardizing the lives of the four Americans on board.

“One of the Russian flares struck the U.S. MQ-9, severely damaging its propeller,” Lt. Gen. Alex Grynkewich, the head of U.S. Air Forces Central, said in a statement describing the latest close call. “We call upon the Russian forces in Syria to put an immediate end to this reckless, unprovoked, and unprofessional behavior.”

Grynkewich said one of the crew members operating the drone remotely kept it in the air and flew it back to its home base.

The Sunday incident is the latest in a series of encounters between Russian fighter jets and U.S. aircraft flying over Syria. U.S. leaders have noted the uptick and so far have discounted any connection to Russia’s ongoing war in Ukraine, where the U.S. and Western allies are actively supporting Kyiv’s fight against Moscow.

Army Gen. Mark Milley, chairman of the Joint Chiefs of Staff, said he’s uncertain what triggered the increase. “We’ve got analysts trying to figure that out. I don’t know if it’s connected to Ukraine or not. Right now, there’s nothing to suggest that it is,” he told reporters during a recent briefing.

Others have suggested that it stems from a growing coordination among Russia, Syria and Iran and is meant to persuade the U.S. to leave Syria, thus opening the door for more Iranian activity, particularly in the South.

In all of the intercepts except the one instance a week ago, the U.S. aircraft were MQ-9 drones without crew members. On that Sunday, however, the Russian Su-35 jet few close to a U.S. MC-12 surveillance aircraft with a crew, forcing it to go through the turbulent wake.

U.S. officials at the time called it a significant escalation in the ongoing string of encounters between U.S. and Russian aircraft that could have resulted in an accident or loss of life. They said the Russian move hampered the crew members’ ability to safely operate their plane.

In recent weeks, U.S. officials said, Russian fighter jets have repeatedly harassed U.S. MQ-9 drones, which are conducting anti-Islamic State group missions, largely in western Syria.

On multiple occasions in the past three weeks, the officials said, Russian fighter jets flew dangerously close to the U.S. Reapers, setting off flares and forcing the drones to take evasive maneuvers.

U.S. and Russian military officers communicate frequently over a deconfliction phone line during the encounters, protesting the other side’s actions.

There are about 900 U.S. forces in Syria, and others move in and out to conduct missions targeting Islamic State group militants.