A few months later, Sharlet was shipped back to South Vietnam, this time on the eve of the January 1964 South Vietnamese coup by General Nguyen Khanh against the junta on January 30. Following the quick success of the coup, Sharlet was reassigned north to Phu Bai Combat Base an Army Security Agency base south the DMZ. There he was attached to Detachment J, a branch of the 3rd Radio Research Unit providing communications support for commando operations in North Vietnam. Sharlet was also seconded to a nearby Marine intelligence unit for Long Range Reconnaissance Patrols. By the time he finished his Vietnam tour late May 1964, Sharlet had seen enough political corruption and military incompetence of the Army of the Republic of Vietnam (ARVN), often compounded by exaggerated, upbeat reports by U.S. military advisors, to become thoroughly disillusioned with U.S. involvement in what he considered a Vietnamese civil war.