BEJA AIR BASE, Portugal – U.S. Air Force Staff Sgt. Christopher Lancaster, 52nd Aircraft Maintenance Squadron aerospace propulsion technician, works on the engine of an F-16 Fighting Falcon fighter aircraft, assigned to the 480th Fighter Squadron at Spangdahlem Air Base, Germany, before it participates in Trident Juncture 2015 at Beja Air Base, Portugal, Oct. 22, 2015. NATO exercises such as Trident Juncture provide an excellent venue for current and hopeful NATO members to work on their warfighting, communication and coordination skills. (U.S. Air Force photo illustration by Airman 1st Class Luke Kitterman/Released)