A U.S. Marine Corps MV-22B Ospreys with Special-Purpose Marine Air-Ground Task Force - Crisis Response - Africa takes off from a runway for Dakar, Senegal, prior to returning to Morón Air Base, Spain, with new pilots, after supporting of Operation United Assistance in Monrovia, Liberia, Dec. 4, 2014. United Assistance is a Department of Defense operation that provides command and control, logistics, training, and engineering support to U.S. Agency for International Development- led efforts to contain the Ebola virus outbreak in West African nations. (U.S. Marine Corps photo by Lance Cpl. Andre Dakis/SPMAGTF-CR-AF Combat Camera/Released)