U.S. Marines disembark a coach bus upon arrival at the Langley Transit Center at Langley Air Force Base, Va., Nov. 13, 2014. Ninety U.S. military personnel from the Air Force, Army, Marine Corps and Navy will undergo a mandatory 21-day controlled monitoring period at the transit center, where they will be separated from the general public in order to be monitored for and deemed clear of any symptoms consistent with the Ebola virus disease. (U.S. Air Force photo by Staff Sgt. Jason J. Brown/Released)