On April 4, NATO fighter jets took off from Amari Airbase in Estonia to escort a Russian TU-134 transport airplane flying from mainland Russia toward Kaliningrad with a pre-filed flight plan and with its onboard transponder on.
It maintained radio communication with air traffic control centres. On its way to Kaliningrad, the aircraft was met by two Russian Su-27 fighter jets with no pre-filed flight plans and with their on-board transponders off.
On April 7, NATO jets stationed in Estonia identified and escorted a Russian Il-76 transport airplane flying from Kaliningrad to mainland Russia.
The following day, NATO jets took off from Šiauliai Airbase in Lithuania to escort five Russian planes, including an An-12 transport aircraft flying from mainland Russia to Kaliningrad without a flight plan and with its on-board transponder off. It maintained radio communication with air traffic control centres.
The NATO jets also escorted an Il-18 transport plane and a Tu-134 transport plane heading for Kaliningrad from mainland Russia, as well as two Su-27 fighters escorting the Tu-134. The fighter jets were flying from Kaliningrad without a pre-filed flight plan, with their onboard transponders off and without maintaining radio communication with air traffic control centres.