U.S. Air Force WC-135 Constant Phoenix aircraft is refuelled from an air tanker

U.S. Air Force WC-135 Constant Phoenix aircraft is refuelled from an air tanker

A US Air Force WC-135 surveillance aircraft is refueled from an air tanker in an undated picture. Photo: USAF/Handout via Reuters

May 21, 2017 3:41 PM (UTC+8)