During the days of Prince Norodom Sihanouk's rule in Cambodia in the 1960s, the People's Army of Vietnam (PAVN) and their Viet Cong (VC) allies were able to use base areas in Cambodian territory in order to provide logistical support for their combat troops within South Vietnam. Following the March 1970 coup led by the pro-U.S. General Lon Nol, the PAVN aggressively expanded their control over the provinces of northeastern Cambodia, coming dangerously close to the capital Phnom Penh.