A pair of U.S. army planes flying over the Black Sea were scrambled by Russian warplanes on the grounds that they were approaching their borders, Russian defense ministry said Wednesday.

Two Russian Su-30 fighter jets took off to identify detected air targets and prevent violations of the Russian Federation State Border. “Russian fighter crews identified the aerial targets as two U.S. B-1B strategic bombers and 2 KC-135 tanker aircraft escorted over the waters of the black Sea.” The Russian defense ministry statement said. The Russian planes returned to their home bases after turning away the U.S. planes.

It said the Russian aircraft had carried out their flight in strict compliance with international airspace rules.