Harkins had the task of advising the South Vietnamese government on security, organization, and employment of their military and paramilitary forces.
With an initial authorized strength of 216 men (113 Army), MACV was envisaged as a temporary HQ that would be withdrawn once the Viet Cong insurgency was brought under control.
During the year, the U.S. buildup continued, especially in aviation, communications, intelligence, special warfare and logistic units, reaching a total of 17,068 men, of which 10,916 were Army.
Harkins concurred and General James Francis Collins, commander of United States Army, Pacific and Admiral Felt approved the redesignation.
[3]: 37 MACV was reorganized on 15 May 1964, and absorbed MAAG Vietnam within it, when combat unit deployment became too large for advisory group control.
In April 1967, General Westmoreland, who had arrived in June 1964 as Commander of MACV, organized a division-sized blocking force along the border between North and South Vietnam.
On 24 January 1968, General Westmoreland "cabled to Admiral Sharp a recommendation that the Commander in Chief, Pacific (CINCPAC), and MACV begin contingency planning for the use of tactical nuclear weapons in northern Quang Tri if necessary to prevent a major defeat.
Sharp on the thirtieth accepted Westmoreland’s proposal and ordered planners from MACV and CINCPAC’s component commands to meet on Okinawa on 1 February.
Assigning the project the code-name Fracture Jaw, Sharp told all concerned to “bear in mind the very sensitive nature” of the planning and to restrict knowledge of it to as few people as possible on an “absolutely essential need to know basis.”[5] Planning began in January 1968 to move nuclear weapons into South Vietnam so that they could be used on short notice against North Vietnamese troops.
As a result, on 1 April 1966, Naval Forces Vietnam, was established to control the Navy's units in the II, III and IV Corps Tactical Zones.
As the U.S. military presence in South Vietnam grew, MACV quickly outgrew the Pasteur Street quarters and expanded into a proliferating number of buildings throughout downtown Saigon.
He initially tried to obtain a site between the ARVN Joint General Staff compound and Tan Son Nhut Airport, desirable from the standpoint of removing Americans from central Saigon and placing MACV conveniently close to its Vietnamese counterpart.
[11] The Vietnamese government refused to turn over the most suitable location, a soccer field (10°48′45.62″N 106°39′57.49″E / 10.8126722°N 106.6659694°E / 10.8126722; 106.6659694 (post-1967 MACV, Saigon)) near the civilian air terminal, allegedly because Premier Nguyễn Cao Kỳ wanted to keep the property for a postwar tourist hotel.
In late April 1966, with the Saigon regime locked in a tense confrontation with Buddhist and ARVN rebels in I Corps, Ambassador Henry Cabot Lodge Jr. and Westmoreland reopened the effort to acquire the Tan Son Nhut soccer field.
"[12] The air-conditioned complex of two-story prefabricated buildings, a little more than a third the size of its Washington namesake, included twelve acres of enclosed office space.
In addition to the headquarters offices, the complex included a barracks, a mess hall, a refrigerated storage building and its own power plant and telephone exchange.
Under the terms of the Paris Peace Accords MACV and all American and third country forces had to be withdrawn from South Vietnam within 60 days of the ceasefire.
Transfer of the main body, drawn largely from the operations and intelligence sections of MACV and Seventh Air Force, began on 10 February.
[15]: 52 The DAO was activated on 28 January 1973 with United States Army Major General John E. Murray, formerly MACV director of logistics, as the Defense Attaché and United States Air Force Brigadier General Ralph J. Maglione, formerly the MACV J-1 (Director for Manpower and Personnel), as deputy Defense Attaché.
At 11:00 on the 29th, in a simple ceremony, General Weyand furled the colors of the Military Assistance Command, Vietnam, and formally inactivated it.