Washington (CNN) A Russian fighter jet acted in an "unsafe manner" during a Tuesday encounter with NATO aircraft, with the Russian jet almost cutting into the flight path of a NATO plane, forcing the alliance jet to maneuver to avoid a dangerous situation, a NATO military official tells CNN.

The incident occurred Tuesday when two Spanish F-18 fighter jets assigned to the NATO Baltic Air Policing mission were scrambled to identify a Russian Tu-214 transport aircraft that was being escorted by two Russian Su-27 fighter airplanes over the Baltic Sea, close to NATO member airspace.

The NATO official said the Russian fighters were flying without a flight plan and had their transponders switched off, behavior NATO officials say can put civilian and military aircraft operating in the area at risk.

The Russian news agency TASS reported that the Tu-214 was transporting Defense Minister Sergey Shoygu, who was flying to the Russian controlled exclave of Kaliningrad.

NATO officials said they had no official information as to who was aboard the aircraft.

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