U.S. Air Force aircrew from the 351st Air Refueling Squadron and crew chiefs from the 100th Aircraft Maintenance Squadron review a pre-flight checklist together prior to a flight supporting exercise Joint Warrior 19-1 at RAF Mildenhall, England, April 4, 2019. Joint Warrior is a U.K.-led multinational exercise that involves numerous warships, aircraft, marines and troops. (U.S. Air Force photo by Tech. Sgt. Emerson Nuñez)