During 1991-1992, the former Yugoslavia began to split apart with civil war. In the spring of 1992, U.S. Forces helped to keep food and medical supplies flowing into Bosnia. Air operations were the vital part of the operation, though a hospital and a treatment center for UN Protection Forces were established. In this center, U.S. Army, Navy, and Air Force units rotated every six months. When the mission ended in January 1996, it was the longest humanitarian airlift operation performed by the Department of Defense.