South Vietnamese [came] "close......to annihilating or capturing the core of the Southern resistance - elite units of our frontline fighters along with the civilian and much of the military leadership."

Central Office for South Vietnam (abbreviated COSVN /ˈkɑːzvɪn/; Vietnamese: Văn phòng Trung ương Cục miền Nam), officially known as the Central Executive Committee of the People’s Revolutionary Party from 1962 until its dissolution in 1976, was the American term for the North Vietnamese political and military headquarters inside South Vietnam during the Vietnam War. It was envisaged as being in overall command of the communist effort in the southern half of the Republic of Vietnam (South Vietnam), which included the efforts of both People’s Army of Vietnam (PAVN), the Viet Cong, and the People’s Revolutionary Party.

Whether COSVN actually existed, and if so, where it was located at any one time, and how important it might have been, were contentious subjects, but in his memoirs the American commander in South Vietnam, General William Westmoreland, spoke of it as something whose existence and importance were not in doubt.^[2] Though the COSVN continued to exist in the later years of the war, it could not maintain Viet Cong activities, as the group was effectively destroyed in the aftermath of the 1968 Tet Offensive.