SNIE 63.1-4-55 CONSEQUENCES OF POSSIBLE US COURSES OF ACTION WITH RESPECT TO VI

Created: 9/13/1955

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SPECIAL

NATIONAL INTELLIGENCE ESTIMATE

CONSEQUENCES OF POSSIBLE US COURSES OF ACTION WITH RESPECT TO VIETNAM

Submitted by the

OF CENTRAL INTELLIGENCE

The /allowing Intelligence organizations participated in the preparation of this tttimaU: The Central Intelligence Agency and the intelligence organization* of the Departments ol State, the Army, the Navv, the Air Force, end The Joint Staff.

Concurred tn by the

INTELLIGENCE ADVISORY COMMITTEE

oneptember IMS. Concurring were the Special Assistant, Intelligence, Department of State; the Assistant Chief of, Department of the Army; the Director of Naval intelligence; the Director of Intelligence, xlSAF; and the Deputy Director for Intelligence, The Joint Staff. The, Atomic Energy Commission Hepretentallve to the IAC. and the Assist-ant Director. Federal Bureau of Investigation, abstained, the subject being outside of their jurisdiction.

COPY NO.

ASSISTANT DIRECTOR,ONE

172

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CONSEQUENCES OF POSSIBLE US COURSES OF ACTION WITH RESPECT TO VIETNAM1

THE PROBLEM

To estimate the deterrent effect on the Viet Minh of certain US courses ofto assess the consequencesS failure to counter overt Viet Minhand to assess the political repercussions of US armed intervention against Viet Minh aggression.

THE ESTIMATE

INTRODUCTORY NOTE

continue to regard as valid thein, namely that duringof the estimate (toWestern and particularly USwith general considerationsover-all Bloc policy, will prevent theopenly invading theethat the present Communist policyinternational tension makesresort to overt aggression.

II. DETERRENT EFFECTS ON THE VIET MINH OF THE US UNDERTAKING SUFFICIENTPOLITICAL, AND ECONOMIC STEPS TO CLEARLY CONVINCE THETHAT OVERT AGGRESSION BY THE VIET MINH AGAINST SOUTH VIETNAM WILL BE MET BY SWIFT AND DETERMINED US ARMED INTERVENTION

assumed US course of actioneven less likely than at presentaggression by the Viet MinhVietnam. The Communists would prob-

possible US courses of acUon considered herein were furnished the intelligencetor the purposes or this cstimntc.

'-Aggression" in this paper Is definediet Minh attack by overt armed forces across the armistice line, orharacter that it can clearly be labeled as aggression and Is generally regarded as such by free world opinion.

ably estimate that: (a) Viet Minh forces alone would not be able to capture South Vietnam in the face of swift and determined US armed intervention; (b) Chinese Communistwould have to be oncale as to seriously risk spreading the war beyondand <c) acquisition of South Vietnam would not be worthisk. Thesewould lead the Communists tofrom overt aggression even if they could see no prospect of winning South Vietnam by other means and believed theyarked superiority in forces locally available.

The assumed US course of action would not in itself precludeommunist decision to Initiate large-scale guerrilla action ln South Vietnam or the clandestine support of such actions by the Viet Minh.

The deterrent effect on the Communists of the assumed course of action would be in-increased if the US made it clear that nuclear weapons would be used. If the US made it clear that nuclear weapons would not be used the deterrent effect would be reduced.the Communists would probablythat the US would not maintainosition if facedeteriorating military situation. In the absence of any clearthe Communists would almost certainly base their plans on the possibility that nuclear weapons would be used.

SEC

III, CONSEQUENCESS FAILURE TO INTERVENE AGAINST AN OPEN VIET MINH ATTACK AFTER HAVING TAKEN THE PRERARATORY STEPS ASSUMED IN II ABOVE

Tho Communists would vigorously exploit the opportunities in Asia created by theof the US to intervene in Vietnam.Communist China and the Viet Minh would probably not launch early overtagainst other countries, Chinesediplomacy would probably become openly threatening, possibly supplemented by intim-idatory troop movements near the Chinese Communist border with Burma and Laos or within Communist-held Vietnam.policy would also be furthered by greatly increased support from overseas Chinese

Tlie Chinese Communists would probably apply strong pressure against those countries whose determination to resist Communisthad been most weakened. They would demand an accommodation to the Bloc going beyond the benevolent neutralism that is the current goal of Communist strategy in much of the area. Where more forceful actionnecessary, Peiping would almostencourage local Communist groups to resume and enlarge guerrilla operations and would support those operations more directly than in the recent past. In some cases units of Chinese Communist troops, possibly oforigin, might be assigned to reinforce local guerrilla units. Communist operations against the offshore islands might be stepped up,ull-scale attack against Taiwan would probably not be initiated.

The consequencesS failure toto save South Vietnam would be most serious in Asia. US prestige and influence would be drastically lowered, and the Manila Pact as an effective instrument againstaggression would almost certainly be destroyed. Even immediate and forcefulUS action elsewhere in Southeast Asia might not persuade any state In the area that further Communist pressure could be resisted. These countries would be reluctant to accept

US offers of assistance from fear that closer alignment with the US would merely Invite the Communists to further acts of aggression and that in such an event US assistance would not be forthcoming. They would becomeInclined to attempt to maintain their independence through negotiatedwith Peiping.

Both Laos and Cambodia would probably initiallyeutralist position but would shortly enter into cultural andagreements with Communist China as the first steps toward politicalThai apprehensions for their ownwould greatly increase. Successive government changes might bring toeadership amenable to an accommodation with Communist China. Burma wouldnot consider such Communist actionirect threat and would seek to remainShould the Thai government reach an accommodation with the Communists, Burma would become concerned and would probablyloser alignment with India. The British would be gravely concerned over the security of Malaya and would almost certainly press for the commitment of US forces to the defense of Malaya. Although the Philippines, South Korea, and Nationalist China would remain allied with the US, they would have grave doubts concerning the future. They would almost certainly press the USore concrete demonstration of itsto defend them. In Japan, neutralist sentiment would increase. Indonesia would attempt toeutral orientation but would be drawn toward an accommodation with the Communist Bloc as Communistspread through mainland Southeast Asia.

The reactions of the Western European allies of the US would be mixed. On the one hand, they would be concerned about the implications of US withdrawal in the face of an open Communist attack, and there would probably be an increase in defeatist andsentiment. On the other hand, wethat these concerns would tend to be offset by their reliefrisis in the Far East had not ledenewal of armed con-

diet which might embroil them in general war. In any event, the Europeans would notconclude that the US would fail to resist Communist aggression in Western Europe. Middle East defense arrangements mightmore difficult becauseoss ofin US commitments.

IV. CONSEQUENCESAILURE OF THE US TO INTERVENE AGAINST AN OPEN VIET MINH ATTACK WITHOUT HAVINGMADE INTENTIONS CLEARER THAN THEY ARE AT PRESENT

he local reactions to the US failure to intervene under these conditions would be virtually the same in Southeast Asia as they would be under the conditions discussed in Section III above. It is widely believed in Southeast Asia that the US is alreadythrough the Manila Pact to the defense of South Vietnam and that it has strong moral obligations to the Diem government.if the US had made its Intentions no clearer than at present, the Communists would be less inclined to believe that the US failure to intervene indicated that the US would not resist Communist aggressionThe Communists might thereforemore cautiously in their efforts to exploit the situation created by the fall of SouthOutside Southeast Asia, the damage to US prestige and the decline in the will toCommunist pressure would be less than under the conditions discussed in Section III above.

V. CONSEQUENCES OF US ARMEDIF THE US (a) STATED ITSWAS LIMITED TO RESTORING THE STATUS-QUO ATh PARALLEL, OR (b) STATED ITS OBJECTIVE WAS TOTHE VIET MINH REGIME ANDNON-COMMUNIST CONTROL TO ALL VIETNAM

Asian and European approval of US armed Intervention against clearly recognizableaggression would be tempered Indegrees by the 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 and to keep its military actions clearly consonant with that objective. They would be deeply concerned if the US declared itsto be the destruction of tho Vict Minh regime, or carried the fighting beyondIndia and other neutrals would exert every effort to bring the fighting to an end.

The other nations of mainland Southeast Asia would be encouraged in their efforts to resist Communist pressure by USThey too, however, would fear that the fighting could not be limited to Vietnam and that they would become embroiled inwar in the Far East. Only Nationalist China, the ROK, and possibly Thailand and tlie Philippines, would giveS declaration that its objective was to destroy the Viet Minh regime and extend non-Communist control to all Vietnam.

The Communist reactions to USwould probably depend on tho course of US military actions rather than on anyof US objectives.

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