WASHINGTON, Sept. 7 (UPI) — A Russian fighter jet flew within 10 feet of a U.S. reconnaissance aircraft over the Black Sea, the Pentagon said Wednesday.

U.S. military officials said the Russian SU-27 jet made a “dangerous and unprofessional” maneuver in coming that close to the the U.S. Navy P-8A Poseidon aircraft over international waters. The Russian Defense Ministry said the fighter jet was following international protocol with an American plane that was close to Russian territory.

The 19-minute incident began with the Russian jet moving to within 30 feet of the P-8A, then it closed in to 10 feet, officials said. The crew of the U.S. craft tried to contact the pilot of the SU-27 but got no response.

“U.S. Navy aircraft and ships routinely interact with Russian units in the area and most interactions are safe and professional,” said Capt. Jeff Davis, a Pentagon spokesman. “However, we have deep concerns when there is an unsafe maneuver. These actions have the potential to unnecessarily escalate tensions between countries, and could result in a miscalculation or accident, which results in serious injury or death.”

The interaction between Russian and American military planes and warships has become more tense in recents months.