159. Memorandum From the Joint Chiefs of Staff to Secretary of Defense McNamara1



  • US Policy and Actions to Deal with Cambodian Support of the Viet Cong (S)
(TS) Recent studies by both the United States Intelligence Board (USIB) and the Defense Intelligence Agency (Appendix A)2 conclude that the Viet Cong (VC) use Cambodia for a source of supply, for a sanctuary, and for temporary military facilities. Supplies in the form of weapons, ammunition, medicine, and chemicals used in munitions have been captured during actual infiltration into South Vietnam (SVN) from Cambodia. There is considerable evidence, including reports of US Special Forces advisors, that the VC use Cambodian territory in some areas along the 600-mile border for sanctuary. There is also evidence that the VC have established temporary military facilities, such as rest camps, training areas, hospitals, workshops, and storage depots on Cambodian soil. Recent reports3 from Phnom Penh disclose that Prince Sihanouk may start trading openly with the VC. Cambodiaʼs deteriorating financial position may have led Sihanouk to reason that the advantages of trade arrangements with the VC would outweigh any sanctions brought to bear against him by Saigon or the United States.
(TS) Although the Cambodian Government has been careful not to provide the VC military support and has asserted its neutrality. Cambodians do permit the use of their territory and resources by the communist insurgents. This VC use of Cambodian territory is made possible by some active cooperation with the VC at lower Cambodian Government and military levels, an indifferent attitude by other officials, and the inability or failure of the Government to control or even patrol its frontiers. By permitting its country to be used as a source of supply, as a sanctuary, and for military facilities, Cambodia has forfeited its claim of neutrality.
(TS) Recent reports indicate a continued buildup of VC/Peopleʼs Army of Vietnam (PAVN) troops in SVN. The increased requirements of this larger force (including a significant increment of regular troops), the determined Government of Vietnam/United States(GVN/US) efforts to [Page 353] seize the initiative in Southeast Asia, and the resulting higher level of military activity are causing the VC, as the USIB study points out, to place increasing dependency on outside sources of supply for arms and ammunition, technical equipment, medical supplies, cadre personnel, and trained technicians. With the GVN/US efforts to minimize infiltration through other land and sea routes being intensified, the importance of Cambodia to the VC insurgency can be expected to increase as the one remaining unimpaired support route available to them. The Cambodian sanctuary provides the VC with a decided military advantage and has a detrimental effect on the war effort in SVN.
(TS) The Joint Chiefs of Staff have weighed the pros and cons of the specific actions that would be required to minimize Cambodian support of the VC and consider that the following factors are important to a resolution of the problem:
Cambodia is the only contiguous source of VC support against which no action is being taken. Since control of the insurgency involves seeking out and destroying the VC/PAVN forces and their sources of support, the reasons for taking action in this remaining area are militarily clear.
From a political viewpoint, the Joint Chiefs of Staff recognize a risk of antagonizing Prince Sihanouk by any forceful action, with a possibility that Cambodia may seek a closer relationship with Communist China. Although Democratic Republic of Vietnam (DRV) and/or ChiCom intervention appears unlikely, some increase in ChiCom military assistance to Cambodia may be expected.
The possible benefits derived from GVN/US observance of the inviolability of the Cambodian border must be weighed against the violation of South Vietnamese sovereignty by VC incursions into SVN and their use of Cambodia as a sanctuary. SVNʼs fundamental right of self-defense is compromised by a policy that prohibits effective counteraction. Further, the use of Cambodian territory by the VC, with immunity to pursuit, unduly inhibits field commanders in the defense of their areas and forces.
(TS) The Joint Chiefs of Staff consider that the military requirements are of paramount importance and that forceful action must be taken to stop the use of Cambodian territory for VC logistics and sanctuary despite possible adverse political and military reaction.
(TS) It is understood that the Department of State is now in the process of reviewing US policy toward Cambodia. The Joint Chiefs of Staff consider that this revision should be conducted on a priority basis. They have observed that relations with Cambodia have not improved as a result of current and past policies and that support of the VC is continuing. They consider that the present state of affairs, in which Cambodians [Page 354] are supporting the VC, is inconsistent with continued US recognition of Cambodian neutrality.
(TS) US policy toward Cambodia should provide for GVN/US action which will result in minimizing Cambodian support of the VC, including the reduction of infiltration of war materiel into SVN from Cambodia. In this regard, the Joint Chiefs of Staff have considered courses of action to accomplish that objective. Although there are risks associated with the application of the more severe courses of action, the Joint Chiefs of Staff consider that Cambodiaʼs political and military reactions will be insignificant in relation to the gains made possible through suitable application of the pressures and actions recommended. These courses of action are:
Course of Action A. Expand and intensify the over-all 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.
Course of Action C. Encourage third country 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 communication (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 materiel 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.

Details of each course of action are contained in Appendix B.

(TS) The Joint Chiefs of Staff conclude that Courses of Action A through G are appropriate and necessary for immediate implementation and that Courses of Action H and I may be necessary at a later date.
(TS) The Joint Chiefs of Staff recommend that:
US policy toward Cambodia include, as an objective, the denial of Cambodian territory for the support of the VC insurgency.
Courses of Action A through G be approved for immediate implementation.
Courses of Action H and I be reserved for consideration pending the outcome of Courses of Action A through G.
A memorandum substantially as contained in Appendix C be forwarded to the Secretary of State.
For the Joint Chiefs of Staff:
David L. McDonald 4
Acting Chairman
Joint Chiefs of Staff
  1. Source: Washington National Records Center, RG 330, OASD/ISA Files: FRC 70 A 5127, Cambodia 000.1—, 1965. Top Secret.
  2. All appendices are attached, but not printed.
  3. Amembassy Bangkok msg 041125Z (JCS IN 36637) and CIA msg [less than 1 line of source text not declassified] (JCS IN 40032). [Footnote in the source text.]
  4. Printed from a copy that indicates McDonald signed the original.