Two U.S. Air Force F-16 Fighting Falcons, from the New Jersey Air National Guard's 177th Fighter Wing, fly in formation over Bulgaria during Thracian Star on July 20, 2015. Thracian Star 2015 is a bilateral training exercise to enhance interoperability with the Bulgarian air force, hosted by Graf Ignatievo Air Base. (U.S. Air National Guard photo by Master Sgt. Andrew J. Moseley/Released)