The Pentagon has said a Russian fighter jet came within 10 feet of a U.S. Navy surveillance plane over the Black Sea. The U.S. Department of Defense said its plane was conducting routine operations in international airspace on Wednesday.

The Russian Defense Ministry said in response that Moscow had to scramble Crimea-based “SU27” fighter jets to intercept the U.S. spy plane. It said the plane was attempting to approach the Russian airspace over the Black Sea. The ministry also said the U.S. plane was flying with its transponders switched off.

According to the Pentagon, a Russian “SU27 Flanker” first maintained a distance of 30 feet, then closed to within 10 feet of the “USP8A Poseidon” electronic signals aircraft. The intercept occurred at 11:20 a.m. local time and lasted about 19 minutes. Russia said the U.S. plane made two attempts to approach its airspace.