Foreign Relations of the United States, 1955–1957, Vietnam, Volume I

260. Memorandum From the Secretary of State’s Special Assistant for Intelligence (Armstrong) to the Acting Secretary of State¹

Washington, September 9 [30?], 1955.

SUBJECT

• SNIE 63.1–4–55: Consequences of Possible US Courses of Action with Respect to Vietnam²

At the request of the NSC Planning Board, the intelligence agencies have examined the consequences of certain specified US courses of action with respect to Vietnam and have arrived at the following principal conclusions which were approved by the Intelligence Advisory Committee on September 13, 1955:

1. If the US were to undertake sufficient military, political, and economic steps to clearly convince the Communists that overt aggression by the Viet Minh against South Vietnam will be met by swift and determined US armed intervention, such aggression would be most unlikely.

2. If, after taking the preparatory steps assumed in point 1 above, the US failed to intervene against an open Viet Minh attack, US prestige and influence in Asia would be drastically lowered and the Manila Pact as an effective instrument against Communist aggression would almost certainly be destroyed. The Chinese Communists would probably apply strong pressure against those countries whose determination to resist Communist inroads had been most weakened. As a result, the free nations of mainland Southeast Asia would become increasingly inclined to attempt to maintain their independence through negotiated understandings with Peiping.

3. If the US failed to intervene against an open Viet Minh attack without previously having made its intentions clearer than they are at present, the local reactions in Southeast Asia would be virtually the same as those noted in point 2 above. The Communists, however, would be less inclined to believe that the failure to intervene indicated that the US would not resist Communist aggression elsewhere. They might therefore proceed more cautiously in their efforts to exploit the situation created by the fall of Vietnam.

4. If the US intervened against an open Viet Minh attack, Asian and European approval for such action would be tempered by fear that the fighting could not be limited to Vietnam. Our NATO allies and Japan would exert pressure on the US to limit its objective to restoring the status quo. Only Nationalist China, the ROK, and possibly Thailand and the Philippines, would give unqualified support to a US declaration that its objective was to destroy the Viet Minh regime and extend non-Communist control to all Vietnam.

PA

1. Source: Department of State, Central Files, 611.51G/9–3055. Top Secret. A marginal note on the source text in an unidentified hand indicates that Hoover did not see this memorandum before his departure on September 30.
2. For text, September 13, see United States–Vietnam Relations, 1945–1967, Book 10, pp. 997–1000. Special National Intelligence Estimates (SNIEs) were interdepartmental reports presenting appraisals of foreign policy problems on an immediate or crisis basis. SNIEs were drafted by officers from those agencies represented on the Intelligence Advisory Committee, discussed and revised by interdepartmental working groups coordinated by the Office of National Estimates of the CIA, and circulated under the aegis of the CIA to the President, appropriate officers of cabinet level, and the NSC. The Department of State provided all political and some economic sections of SNIEs.