NATO claims two Russian fighter jets made an unsafe and unprofessional approach toward Standing NATO Maritime Group 1 (SNMG1) during routine operations in the Baltic Sea.
The jets flew over the force at an altitude of 300 feet (91 meters) and a distance of 80 yards (73 meters) on Thursday morning after the Russian pilot failed to respond to communications, NATO's Naval Command said.
"NATO deemed the interaction unsafe and unprofessional since it was conducted in a known danger area, which was activated for air defence training, and due to the aircraft altitude and proximity," it said in a statement.
It added that the interaction could have increased the risk of miscalculations and accidents.
It further stated that NATO will respond to any interference in the alliance's activities in the region that endangers the safety of aircraft, ships, or crews.
This comes as the tensions between the Western military alliance and Russia have reached their peak over the military conflicts in Ukraine.
The fear of conflict between the two sides has increased in recent days after a missile hit the territory of Poland, a NATO member, near the Ukrainian border.
NATO has doubled its naval presence in the Baltic and North Sea after the September explosions in Russia-Europe gas pipelines.
NATO's naval group in the Baltic Sea, including Dutch, Norwegian and Danish ships, has been conducting operations to increase cooperation with Finland and Sweden, which are on the way to join the alliance.