A Chinese fighter jet performed “an unnecessarily aggressive maneuver” in front of a U.S. reconnaissance plane in international airspace over the South China Sea last week, the U.S. military said, amid growing concerns over a mishap or accidental clash in the waterway.

The U.S. military’s Indo-Pacific Command said in a statement released Wednesday that the incident had occurred when a Chinese J-16 fighter jet intercepted a U.S. Air Force RC-135 plane last Friday. A 30-second video clip accompanying the statement showed the Chinese fighter appearing to swerve in front of the U.S. plane and the RC-135’s cockpit shaking in the turbulence.

“The PRC pilot flew directly in front of the nose of the RC-135, forcing the U.S. aircraft to fly through its wake turbulence,” the statement said. “The RC-135 was conducting safe and routine operations over the South China Sea in international airspace, in accordance with international law.”