A Russian fighter jet flew dangerously close to a U.S. surveillance aircraft over Syria on Sunday.

Lt. Gen. Alexus Grynkewich said in a statement to The Hill that the incident occurred at about 11:45 a.m. on Sunday, and that the Russian Su-35 fighter jet engaged “in an unsafe and unprofessional manner” with the U.S. M-12 aircraft, which was forced to fly through “wake turbulence” as a result.

“This reduced the crew’s ability to safely operate the aircraft and put the four crewmembers’ lives at risk,” Grynkewich said. “These actions against a manned aircraft represent a new level of unsafe and unprofessional actions by Russian aircraft operating in Syria.”

“We strongly urge Russian forces in Syria to cease reckless and threatening behavior that could result in an accident and loss of life, and adhere to the standards of behavior expected of a professional force,” he added.

The Associated Press first reported the incident, citing officials who spoke on the condition on anonymity.

The officials did not speak on how close the Russian jet got to the aircraft, which was conducting surveillance against Islamic State groups in Syria.

This is just the latest in a series of incidents involving Russian fighter jets harassing U.S. aircraft near Syria in recent weeks. Earlier this month, three Russian fighter jets harassed U.S. drones that were conducting a mission against ISIS over Syria and forced the drones to “conduct evasive maneuvers.”

In March, a Russian jet intercepted a U.S. drone over the Black Sea and forced it down. U.S. officials have also decried these incidents as “unprofessional” and “unsafe.”

The Hill has also reached out to the National Security Council for comment.