During the Vietnam War, the Military Assistance Command, Vietnam Studies and Observations Group (MACVSOG) was a highly-classified, U.S. joint-service organization that consisted of personnel from Army Special Forces, the Air Force, Navy SEALs, Marine Corps Force Reconnaissance units, and the CIA. This secret organization was committed to action in Southeast Asia even before the major build-up of U.S. forces in 1965 and also fielded a division-sized element of South Vietnamese military personnel, indigenous Montagnards, ethnic Chinese Nungs, and Taiwanese pilots in its varied reconnaissanc