1st Air Force (Air Forces Northern) Commander, Lt. Gen. William H. Etter talks with Mexican Air Force LNO, Lt Col Ruben Cortes Hernandez during the Ardent Sentry 15 Exercise held at Tyndall Air Force Base, Fla. Ardent Sentry 15 marked the first time that Mexican military personnel had participated in the exercise with American forces at Tyndall AFB. (U.S. Air Force Photo by Mary McHale/Released)