(VOVworld) – The joint air force drill ‘Thracian Star 2016’, involving units from NATO members including Bulgaria, the United States, Greece, and Romania, began in the Bulgarian airspace on Monday, Bulgarian officials said.

US parachutists in joint military exercise 'Noble Partner' 2016 in Vaziani (Photo: EPA)

During the 12-day exercise, 12 F-15 jets from California's 144th Fighter Wing will train together with Romanian MiG-21s, Greek F-16s, and Bulgarian jets and helicopters such as MiG-29, Su-25, AS 532 AL Cougar, Mi-24 and Mi-17, the Bulgarian Air Force said in a statement on its website.

The purpose of the drill is to enhance interoperability of the Bulgarian Air Force to participate in operations under the auspices of NATO. The drill is a part of the plan for joint Bulgarian-American training and exercises for 2016.