U.S. Marine Corps MV-22B Ospreys assigned to Special-Purpose Marine Air-Ground Task Force - Crisis Response - Africa prepare to take-off in support of Operation United Assistance in Monrovia, Liberia, Oct 11, 2014. Operation United Assistance is part of a comprehensive U.S. Government effort, led by the U.S. Agency for International Development, to respond to and contain the outbreak of the Ebola virus in West Africa as quickly as possible. (U.S. Marine Corps photo by Lance Cpl. Andre Dakis/SP-MAGTF Crisis Response - Africa Combat Camera/Released)