Moscow says it had sent a fighter jet to intercept a U.S. aircraft approaching the Russian border because the American plane had turned off its transponder needed for plane identification.
The Russian Defense Ministry said a statement on April 30 that "all flights of Russian planes are conducted in accordance with international regulations on the use of airspace."
The statement came a day after the Pentagon expressed concerns about a series of incidents involving Russian aircraft that have "come close enough to other air and sea traffic to raise serious safety concerns."
The latest incident occurred on April 29, when a Russian SU-27 fighter intercepted a U.S. Air Force reconnaissance plane as it flew in international airspace over the Baltic Sea.
CNN reported that the Russian jet had come within about 30 meters of the U.S. plane and had performed a barrel roll.
Pentagon spokesman Bill Urban said "this unsafe and unprofessional air intercept has the potential to cause serious harm and injury to all air crews involved" and "unnecessarily escalate tensions between countries."
In an earlier incident this month, Russian jets buzzed a U.S. guided missile destroyer, the USS Donald Cook, over the Baltic Sea. A photo released by the Pentagon appears to show the Russian jet passing at an extremely low altitude over the ship's bow.
With reporting by Reuters. CNN, and Interfax