U.S. Air Force Senior Airman Crystal Cash, a boom operator with the 91st Air Refueling Squadron, refuels an F-15 Eagle aircraft attached to the 125th Fighter Wing during Vigilant Shield 15 over the United States Oct. 20, 2014. Vigilant Shield is a weeklong annual exercise designed to emphasize an integrated Department of Defense and civil response in support of the national strategy of aerospace warning and control, defense support of civil authorities and homeland defense. (U.S. Air Force photo by Tech. Sgt. Brandon Shapiro)