150. Memorandum From the Joint Chiefs of Staff to the Secretary of Defense (McNamara)1



  • Concept of Use of SEATO Forces in South Viet-Nam (C)
Reference is made to the memorandum by the Deputy Secretary of Defense, dated 5 October 1961,2 subject as above. The Joint Chiefs of Staff have considered the proposed concept for the use of SEATO forces in South Viet-Nam and the suggested two principal military possibilities for its implementation.
It is their opinion that the use of SEATO forces at the greatest possible number of entry points along the whole South Viet-Nam border, but excluding that part of the 17th parallel now held by the South Vietnamese Army itself, is not feasible for the following reasons:
SEATO forces will be deployed over a border of several hundred miles and will be attacked piecemeal or by-passed at the Viet Cong’s own choice.
It may reduce but cannot stop infiltration of Viet Cong personnel and material.
It deploys SEATO forces in the weakest defense points should DRV or ChiCom forces intervene.
It compounds the problems of communications and logistical support.
Further, the alternative possibility of using SEATO forces to cover solely the 17th parallel, although considered feasible to a limited extent, is militarily unsound in view of the following considerations: [Page 331]
The 17th parallel is not a main avenue of approach being used by the Viet Cong.
North Viet-Nam may interpret such SEATO action as a preparation for aggression against them, thus promoting the possibility of communist harassment and destruction of friendly combat and logistic forces concentrated near the parallel, if not escalation.
As stated in your memorandum, the proposed concept set forth must be analyzed in the total context of the defense of Southeast Asia. Any concept which deals with the defense of Southeast Asia that does not include all or a substantial portion of Laos is, from a military standpoint, unsound. To concede the majority of northern and central Laos would leave three quarters of the border of Thailand exposed and thus invite an expansion of communist military action. To concede southern Laos would open the flanks of both Thailand and South Viet-Nam as well as expose Cambodia. Any attempt to combat insurgency in South Vietnam, while holding areas in Laos essential to the defense of Thailand and South Viet-Nam and, at the same time, putting troops in Thailand, would require an effort on the part of the United States alone on the order of magnitude of at least three divisions plus supporting units. This would require an additional two divisions from the United States.
What is needed is not the spreading out of our forces throughout Southeast Asia but rather a concentrated effort in Laos where a firm stand can be taken saving all or substantially all of Laos which would, at the same time, protect Thailand and protect the borders of South Vietnam.
The over-all objective could best be served by the implementation of SEATO Plan 5/61, or a variation thereof, now. This would accomplish the objective of assisting to secure the border of South Viet-Nam against the infiltration of personnel and material in support of the Viet Cong thus freeing Vietnamese forces to conduct more effective offensive operations in South Vietnam. In addition, this action would stem further communist gains in Laos and, at the same time, give concrete evidence of US determination to stand firm against further communist advances world-wide.
If implementation of SEATO Plan 5, or a variation thereof, is considered a politically unacceptable course of action at this time, there is provided herewith a possible limited interim course of action. This course of action, covered in the Appendices hereto,3 could provide a degree of assistance to the Government of South Viet-Nam to regain control of its own territory, and could free certain [Page 332] South Vietnamese forces for offensive actions against the Viet Cong. While the Joint Chiefs of Staff agree that implementation of this limited course of action would not provide for the defense of Thailand or Laos, nor contribute substantially or permanently to solution of the over-all problem of defense of Southeast Asia, they consider the Plan preferable to either of the two military possibilities described in referenced memorandum

For the Joint Chiefs of Staff:

L.L. Lemnitzer 4
Joint Chiefs of Staff
  1. Source: Washington National Records Center, RG 330, OSD Files: FRC 71 A 6489, Viet-1. Top Secret. Received in the Office of the Secretary of Defense on October 9. Also printed, with minor deletions, in United States-Vietnam Relations, 1945-1967, Book 11, pp. 297-299.
  2. Not found.
  3. Appendixes A and B are printed in United States-Vietnam Relations, 1945-1967, Book 11, pp. 300-311.
  4. Printed from a copy that bears this typed signature.