NATO fighter jets have intercepted Russian jet Su-27 and transport aircraft Tu-134 on April 12. Russian aircrafts flew without radar answerphone, flight plan, and didn't contact the Mission Control Center.
According to Delfi, Russian aircrafts were in the Baltic Sea international zone, flying from mainland Russia to the Kaliningrad region.
On April 15, NATO fighter jets have recognized and escorted two Russian fighter jets and three transport aircrafts.
Transport aircrafts Tu-134 and An-12 flew from the Kaliningrad region to the mainland part of Russia without radar answerphone, but they had a flight plan and radio contact with the Mission Control Center.
On the other hand, IL-76 was flying from the mainland part of the Russian Federation to the Kaliningrad region with a flight plan, switched-on radar answerphone, and it kept in touch with the Mission Control Center.