A U.S. Air Force KC-135 Stratotanker, assigned to the 506th Expeditionary Air Refueling Squadron, prepares to take off May 2, 2018, from Andersen Air Force Base, Guam. The Stratotanker provides the core aerial refueling capability for the United States Air Force. (U.S. Air Force photo by Airman 1st Class Gerald R. Willis)