Members of the 21st Special Tactics Squadron use night vision goggles to spot incoming aircraft in need of refueling during Emerald Warrior 2015 at Eglin Air Force Base, Fla., April 21, 2015. Emerald Warrior is the Department of Defense's only irregular warfare exercise, allowing joint and combined partners to train together and prepare for real world contingency operations. (U.S. Air Force photo by Senior Airman Keith James/Released)