May 13, 1961, 3RD RRU Arrived in Saigon

On May 13, 1961, the Army Security Agency’s (ASA) Third Radio Research Unit arrived in Saigon to provide support to the South Vietnamese military. Its location was the first of many conventional sites that US. cryptologists would establish in South Vietnam.

ASA moved quickly. On April 29, 1961, President Kennedy had approved the expenditure of $1.2 million for equipment and had also accepted the ASA Oplan. Two weeks later, the Third Radio Research Unit established an intercept site at Tan Son Nhut Air Force Base — and began operations within two days of its arrival. This was no easy feat because they had to scrounge up furniture and supplies and clean their headquarters, an old unused air hangar.