U.S. Air Force Capt. Vincent Pellegri, 351st Air Refueling Squadron aircraft commander, performs pre-flight checks during exercise Astral Knight at RAF Mildenhall, England, June 3, 2019. AK19 is a joint, multinational exercise designed to test Integrated Air and Missile Defense capabilities and will involve a combination of flight operations and computer-assisted exercise scenarios. Participants include the U.S. Air Forces in Europe, U.S. Army Europe forces, and members from the Italian and Croatian air forces. (U.S. Air Force photo by Airman 1st Class Brandon Esau)