A Delta IV launches NROL-47, a classified U.S. military payload, from Vandenberg Air Force Base, California. It is the last single-core Delta IV to launch from Vandenberg. [https:--spaceflightnow.com-2018-01-13-delta-4-rocket-successfully-lofts-clandestine-nro-satellite-into-orbit-"(Spaceflight Now)"]