Bulgarian and Greek air forces held a joint flight exercise called Green Bridge 2026 on September 23, the defence ministry said. The goal, it said, was to test how pilots from the two countries hand over and take control of an intruder aircraft during cross-border operations.

The exercise also checked how well Bulgaria's and Greece's air forces work together, and trained pilots for joint flight missions.

Under the scenario, a Spartan military transport plane from the 16th air base played the role of an aircraft that had strayed off its planned route. That triggered the alert procedure used in the allies' shared airspace.

Two Bulgarian MiG-29 fighters intercepted the intruder aircraft, escorted it, then handed it over to a Greek F-16 pair on duty. The Greek pilots carried out an air policing mission and forced the aircraft to land at the designated airport.

Control of the crews passed back and forth throughout the exercise between the two countries' national command and reporting centres, the defence ministry said.

The BTA news agency recalled that 25 years ago, from September 11 to 21, 2001, Bulgaria hosted a multinational air force exercise under NATO's Partnership for Peace programme for the first time — Cooperative Key 2001. Troops from nine NATO member states and 13 Partnership for Peace countries took part.