Sept. 28 (UPI) -- Six U.S. Air Force F-16 fighter planes joined Bulgarian aircraft in a four-week air policing mission over Bulgaria, NATO announced on Monday.
The F-16 Fighting Falcons of the 555th Fighter Squadron, 31st Fighter Wing, stationed at Aviano Air Base in Italy, were deployed to Graf Ignatievo Air Base, near Plovdiv, on Monday after completing the "Thracian Viper 20" international training exercise at the Bulgarian airbase.