Two Russian Su-27 fighters drove away an F-18 aircraft belonging to the North Atlantic Treaty Organization, which attempted to approach the plane carrying Russian Defense Minister Sergei Shoigu on Tuesday.

The Russian Defense Ministry’s Zvezda broadcasting service said the incident took place over the neutral waters in the Baltic Sea.

Shoigu was returning to Moscow from the Russian exclave of Kaliningrad on the Baltic shore, where he attended an international amphibious assault landing troop competition earlier in the day, Zvezda said.