COSVN, pronounced "CÅŽS-vÄn" and standing for Central Office for South Viet Nam, was a North Vietnamese military headquarters (HQ) during the Second Indochina War (Vietnam War). It was in overall command of the communist effort in South Vietnam, which included the efforts of both the Việt Cá»™ng and the North Vietnamese army. Whether COSVN really existed, and if so, where it was at any one time, and how important it was, have been contentious subjects, but U.S. military intelligence generally believed quite certainly that COSVN existed and that it was a valuable target (Westmoreland 1976:55,56,206,389).