Within a year of the Army Security Agency (ASA) setting up its station at Tan Son Nhut in 1961, other elements of the American cryptologic community started to arrive on the scene.

These newly arriving units found themselves in much the same boat as ASA had been in during its first days. They, too, needed a lot of training on the communications environment; plus, they had to develop an operational and organizational niche, that is, they had to “fit in” the growing cryptologic mission. The first to arrive after the army were the U.S. Marine Corps cryptologists.

The Marines Corps almost made it to Southeast Asia during the Laotian crisis of late 1959. Initially, when the ASA command was caught flat-footed by the demands of manning a site in Thailand (as well as supporting the Laotian crisis task force), the Chief of Naval Operations (CNO) offered a team of twenty marines from the 1st Composite Radio Company (COMRADCO), Fleet Marine Force, Pacific (FMFPAC) stationed at Kaneohe, Hawaii. The CNO felt that the Marines could make an “interim contribution” to the army’s effort, and this could enhance the COMRADCO’s capability to direct support possible operations by JTF-116 in Laos.69 However, about a week later, the offer became moot as CINCPAC put JTF-116 on alert and assigned operational control of the marines (designated USN-414A) to the commander of the Marine Expeditionary Force attached to the task force.

In December 1961, the U.S. ambassador to South Vietnam, Frederick Nolting, approached Vietnamese president Diem with a request to increase the cryptologic contingents in South Vietnam. His immediate requirement was for another 236 ASA personnel and a marine unit of forty-three men. Diem approved the additions.”

In January 1962, the marines would finally be deployed in Southeast Asia on a temporary mission designed to last three months. In that month a detachment from the 1st COMRADCO arrived in South Vietnam. They set up at Pleiku in the Central Highlands (USN-414T), and were collocated with an Army of the Republic of Vietnam (ARVN) intercept and direction finding site which, itself, was part of the White birch net (and were supported by three men from the 3rd RRU). The marines spent most of their time training and acclimating themselves to the communications environment. Usually about three officers and forty-five or so enlisted personnel were stationed there, rotating every four months from the field with replacements from the parent company in Hawaii. The unit manned five manual Morse and radiotelephone intercept positions, collecting Cambodian, North Vietnamese, and Laotian communications. The marines received their technical support from the ASA and coordinated intercept missions with the existing army sites.”

Source: Spartans in darkness: American SIGINT and the Indochina War, 1945-1975