Located south of the city of Hue Vietnam, PhuBai was the home of the U.S. Army Security Agency (US ASA) 8th Radio Research Field Station (8th RRFS) and Naval Security Group Det PhuBai was located.
The compound at PhuBai was a very large Combat Base, about 40 miles south of the Demilitarized Zone (DMZ), which separated North Vietnam and South Vietnam. The 8th Radio Research Field Station, 509th Radio Research (RR) Group, was subordinate to the U.S. Army Security Agency (USASA) at the 8th U.S. Army Security Agency Field Station (USASAFS) at Phu Bai. The 8th RRFS was replaced at PhuBai by the 303rd Radio Research Battalion (headquartered at Long Binh) on October 16, 1968.
Designed to provide cryptologic support, the Naval Security Group Detachment, PhuBai, South Vietnam was a detachment of NSG Dept, NCS Philippines, San Miguel, Philippines. COMSEC Unit 705 Det was a detachment of COMSEC Unit 705, co-located with NSG Det Alpha, Danang, South Vietnam, which was located at the U.S. Naval Support Activity, Danang, South Vietnam.
Also designed to give cryptologic support, the 509th Group had four major radio research components; the 303rd Battalion, the 313th Battalion, the 8th Field Station, and the 224th Aviation Battalion. It also had responsibility for the 101st
Radio Research Company (formerly the 7th Radio Research Unit) which directly supported the two major U.S. headquarters in South Vietnam, the Military Assistance Command Vietnam (MACV) and the headquarters, U.S. Army, Vietnam.
On October 6, 1972 all units stationed at PhuBai were evacuated.
Of note, in February, 1963, Company L, Marine Support Battalion moved from Pleiku, South Vietnam, to PhuBai; and from August, 1964 was co-located with NSG Det PhuBai. In early 1971, Company L transferred to NSGA Guantanamo Bay, Cuba.