171. Letter From Secretary of Defense McNamara to Secretary of State Rusk1

Dear Dean:

In light of the United States Intelligence Board (USIB) findings (USIB Study, D–24.7/4 of 28 Oct 65, subject: Infiltration and Logistics—South Vietnam),2 the Joint Chiefʼs of Staff have expressed their views for future U.S. policy and actions to cope with support being given the Viet Cong through Cambodia. Their report to me, JCSM 812–65 of 12 Nov 65,3 was made available to Assistant Secretary of State William Bundy on 16 November 1965 to enable prompt consideration by State and Defense staffs of the proposed courses of action which are briefly stated as follows:

Course of Action A. Expand and intensify the overall intelligence collection program for Cambodia.

Course of Action B. Conduct a political/psychological campaign to persuade the Government of Cambodia to take actions to stop support of the VC.

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Course of Action C. Encourage third-county participation in actions designed to bring pressure against Cambodia to stop support of the VC.

Course of Action D. Increase surveillance of the sea lines of communications (LOCs) between the RVN and Cambodia and increase controls on the Mekong and Bassac waterways.

Course of Action E. Conduct covert paramilitary operations into Cambodia to reduce the infiltration of personnel and material and to collect intelligence information.

Course of Action F. Conduct low altitude aerial reconnaissance into Cambodia.

Course of Action G. Authorize GVN/US operations into Cambodia in immediate pursuit of VC forces which are withdrawing into Cambodian territory.

Course of Action H. Conduct military operations to prevent entry of maritime shipping carrying contraband goods into Cambodian ports.

Course of Action I. Conduct overt air and/or ground cross-border operations into Cambodia against confirmed LOCs and facilities which support the VC insurgency.

I am of the opinion that unless there is a sudden, significant increase in either use of Cambodian territory by the PAVN/Viet Cong or step-up in logistical support from that country, a gradual response by the U.S. Government and certain other friendly governments is both appropriate and desirable. My thoughts on each of the proposed courses of action are as follows:

Course of Action A. Foremost in importance, I feel, is the need to expand and intensify the overall intelligence collection program for Cambodia, since decisions on other courses of action may hinge largely upon the availability of timely, reliable information concerning activities in Cambodia related to PAVN/Viet Cong operations. To this objective, I request your concurrence in the attached memorandum to Admiral Raborn proposing enhancement by the CIA of its efforts with respect to Cambodia.4 This, of course, is additional to what can be accomplished in the area by the Defense Intelligence Agency and your Bureau of Intelligence and Research by way of intensifying their programs.

Courses of Action B and C. These seem to fall entirely within your purview and I recognize the far-ranging implications in the international arena. I fully share the concern of the Joint Chiefs of Staff and urge that [Page 376] the Government of Cambodia be made acutely aware of all hard evidence now existing or which may be developed in the future that the Viet Cong are being supported from Cambodian territory, or using this territory as a sanctuary, together with appropriate reactions of the U.S. Government to such illegal activities. I would appreciate your views as to what may be possible of accomplishment in the political sphere.

Course of Action D. I have directed the Joint Chefs of Staff to intensify Market Time5 operational surveillance of the sea lines of communications (LOCs) between RVN and Cambodia and to make more effective the controls on the Mekong and Bassac waterways, without violating the Cambodian border, territorial waters, or legitimate rights of navigation.6 Implementation of this course of action will, of course, demand concurrent enlargement of efforts by the Government of South Vietnam. You will be consulted on all aspects of these plans.

Courses of Action E and F. I do not propose a policy decision at this time for conducting paramilitary operations and low level aerial reconnaissance into Cambodia, but believe we should plan to be ready for such operations. As indicated by the Joint Chiefs of Staff, these are effective methods of supplementing other intelligence means. For example, the initial experience with Shining Brass7 reconnaissance/intelligence teams suggests that the selective introduction of highly trained military personnel in cross-border operations could be effective in obtaining reliable information on infiltration activity leading to more effective harassment and interdiction of supply routes.

Since it is only prudent to be prepared for launching cross-border and/or low level aerial reconnaissance, I have informed the Joint Chiefs of Staff that, if the problem with Cambodia grows, consideration will be given on a case-by-case basis to undertaking such actions.

Course of Action G. As you know, the question of immediate pursuit of PAVN/Viet Cong into Cambodia has been separately coordinated with the Department of State as matter of special urgency, and agreed policy is contained in Joint State/Defense message 1634 (DTG 112319Z Dec 65), to the American Embassy, Saigon, and to the Joint Chiefs of Staff, subject: “Authorization for Operations Involving Cambodia”.8 At this time, I have no additional proposals related to this course of action.

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Courses of Action H and I. I am of the opinion that it is premature to seek decision with respect to overt actions against Cambodian sea and land LOCs, but planning will proceed so that we may be prepared to consider such operations if developments should warrant.


  1. Source: Department of State, Central Files, POL 32–1 CAMB–VIET S. Top Secret.
  2. Not found.
  3. Document 159.
  4. In a separate letter to Director of Central Intelligence Raborn, also December 29, McNamara elaborated further on JCS recommendations to expand and intensify intelligence on PAVN/VC activities in Cambodia. McNamara reiterated JCS recommendations for intelligence agent collection nets in Cambodian cities, ports, and areas adjacent to the South Vietnamese border; high altitude reconnaissance; and covert cross-border intelligence-gathering teams. (Department of State, Central Files, POL 27 ASIA SE)
  5. Market Time was the code name of a U.S.-GVN coastal patrol operation to prevent seaborne infiltration. It was begun on March 11, 1965.
  6. In a December 29 memorandum from McNamara to the Joint Chiefs. (Department of Defense, JCS Official Records, 9155.1 (14 Oct 65))
  7. Shining Brass was the code name for U.S.-led South Vietnamese intelligence probes of the Ho Chi Minh Trail in the Laos panhandle. See Foreign Relations, 1964–1968, volume XXVIII, for extensive documentation on it and its successor operations.
  8. See Document 166.