Foreign Relations of the United States, 1964–1968, Volume XXVII, Mainland Southeast Asia; Regional Affairs

208. Memorandum From the Assistant Legal Adviser (Aldrich) to the Assistant Secretary of State for East Asian and Pacific Affairs (Bundy)¹

Washington, September 11, 1967.

SUBJECT

• Proposals to Inhibit NVA/VC Exploitation of Cambodian Territory

The Joint State/DOD/CIA Study Group on Cambodia is presently considering proposals for certain diplomatic and/or military actions to inhibit or guard against enemy exploitation of Cambodian territory. L/EA has been asked a number of pertinent questions concerning the legal rights and obligations of so-called neutrals and belligerents under contemporary international law. These questions are answered in the memorandum attached at Tab A.² The basic conclusions are (1) a neutral is obligated to take measures within its power to prevent the movement of forces or the establishment of bases on its territory by the parties to the conflict; (2) violations of a stateʼs neutrality and territorial integrity by one party to an international conflict do not justify violations by opposing parties; (3) participants in international conflict, including those who are engaged in collective defense against armed attack, may not take military actions on the territory of a neutral third country except in self-defense against armed attack; and (4) pacific means of settlement must be exhausted before the conflict is extended to a “neutral” state.

Cambodia may not have taken all the measures which reasonably can be expected of it to enforce its neutrality, but the remedy for such shortcomings is diplomatic, or legal, not military. Armed reconnaissance patrols on Cambodian territory can be defended only to the extent that they are necessary means of defending U.S. and friendly forces against enemy forces operating in Cambodia and posing a threat so serious that it must be countered. In this memorandum, L/EA analyzes the Cambodian problem in light of the applicable rules of law and U.S. policy objectives and recommends a course of action consistent with our international obligations.

Recommendations:

1. No decision should be taken to expand Daniel Boone operations in Cambodia until the offices concerned have had the opportunity to review (a) a detailed analysis of suspected enemy troop dispositions in Cambodia and the threat they pose to friendly forces in border areas of South Viet Nam, and (b) a full statement of the public justification we would be able to make for our action in the very likely event of disclosure.

2. Before deciding to expand Daniel Boone operations, we should undertake a major diplomatic effort to (a) inform Sihanouk of the extent of NVA/VC use of Cambodia territory; (b) persuade him that failure to prevent such abuse, or to limit its growth, will create a greater risk for Cambodia than would remedial action; and (c) create sufficient international interest and concern to give Sihanouk a justification for acting, i.e., for putting pressure on the NVA/VC to restrain their activity in Cambodia, and/or for seeking an international presence to protect Cambodiaʼs frontiers. The specific diplomatic measures, depending on the strength of our public case, could include bilateral approaches to the Cambodian Government, approaches to Sihanouk by influential leaders of third countries, a new high level approach to the Indian Government to attempt to activate the ICC, and initiatives in the United Nations.

3. In the interim, aerial reconnaissance of Cambodia and other intelligence measures should be continued at present levels to guard against a major build-up of enemy forces in Cambodia. Daniel Boone missions in areas other than the present operating area could be authorized on a case-by-case basis in those situations where, because of the specific disposition of friendly forces, reports of hostile activity in Cambodia, and other factors, it is believed that there may be an immediate serious threat to friendly forces from enemy forces on the Cambodian side of the border.

A. The Problem: NVA/VC Exploitation of Cambodian Territory

There is no doubt that North Viet Nam and Viet Cong forces consist-ently violate Cambodian neutrality. There are, however, no confirmed reports of major NVA/VC troop dispositions on Cambodian territory. The Vietnamese Communists have used Cambodian territory in a variety of ways to support their insurgency in South Viet Nam, but the extent and significance of their use is uncertain. The most important use of Cambodian territory probably has been as temporary sanctuary from US/ARVN operations. Cambodia is also used for infiltration of personnel from North Viet Nam, and bases have been established to provide rest areas, medical care, and possibly training for enemy forces. On occasion U.S. and friendly forces are fired upon from Cambodian territory, and there are reports that certain enemy headquarters operate in Cambodia. The most extensive base areas are located in northeast Cambodia, in Ratanakiri province, and in southeast Mondulkiri province. There is also considerable enemy activity adjacent to South Viet Namʼs Tay Ninh province. These activities violated Cambodiaʼs rights as a neutral and infringe upon the territorial integrity of the state.

The Viet Cong have also procured considerable rice, some medicines, and other supplies in Cambodia. Although this traffic may violate Cambodian and/or South Vietnamese laws, it is not inconsistent with Cambodiaʼs status as a neutral.

SNIE 57–67, January 26, 1967,³ concludes that the availability of Cambodian territory is of considerable psychological and military advantage to the Communists. Denying that territory to the enemy would make life more difficult for the Communists. However, “it would not constitute a decisive element in their ability to conduct military operations in South Viet Nam.”

U.S. commanders believe that Communist use of Cambodia as a sanctuary and source of supply continues to increase as U.S. military superiority makes it more difficult for Communist units to operate in South Viet Nam. A number of enemy units are located in areas of South Viet Nam close to the Cambodian border and there is concern that these forces might be utilizing Cambodian territory to avoid contact with U.S. forces or to prepare for operations against US/ARVN positions. However, as far as we are aware, the conclusions of SNIE 57–67 are still considered valid. The extent of enemy exploitation of Cambodian territory is not certain, but that activity is not believed to be a “decisive element” in the enemy effort.

B. Cambodiaʼs Policy of Neutrality

The Cambodian government has assumed an official posture as a “neutral” in the conflict in Viet Nam, and its actions generally conform with a policy of non-participation in the war. Cambodian forces have not joined in the fighting in South Viet Nam, and so far as we can determine, the Cambodian government has not authorized use of its territory by the Communist forces or supplied arms to them. Prince Sihanouk reportedly has given instructions that no Vietnamese forces be permitted sanctuary or bases in Cambodian territory, and in recent weeks he has made increased efforts to curtail the illicit rice trade with the Viet Cong. Cambodiaʼs official position is strengthened by the Princeʼs request to the International Control Commission to expand its activities to investigate alleged border incursions.

Sihanouk continues to deny the presence of NVA/VC forces on Cambodian territory, but we presume that he is generally aware of VC activity in Cambodia, although perhaps not of the full extent of that activity, particularly in the northeast. Recent reports suggest that some information is withheld from the Prince by subordinates. There are numerous reports that Cambodian military personnel in the border areas have, in some instances, cooperated with NVA/VC forces transiting Cambodia.

The RKG could do more than it has to prevent abuse of Cambodian neutrality, but there are definite limitations on Cambodiaʼs ability to deny its territory to the enemy. Cambodiaʼs military forces are small and many are devoted to the sensitive border with Thailand. Further, Sihanouk must contend with serious pressures from Communist China and from strong left wing elements in Cambodia. In these circumstances, the RKG may have decided to tolerate a limited use of its territory, e.g., for infiltration, temporary sanctuary and convalescence, which in any event it could not effectively prevent, in hopes that the substances of its neutrality would be respected. There are no confirmed reports of major NVA/VC troop dispositions on Cambodian territory or of complicity of the RKG in the enemy war effort.

In view of the enemyʼs limited use of Cambodian territory to date, and the limited capacity of the Cambodian government to protect its territory from all abuse, Cambodia cannot be said to have abandoned or substantially compromised its policy of non-involvement in the conflict. We would like to see Cambodia take official notice of and protest NVA/VC abuse of its territory; to appeal to the United Nations or to third countries to intervene to protect its neutrality; or quietly to seek the support of the Soviets to restrain North Vietnamese activity in Cambodia. However, in view of the problems confronting Prince Sihanouk and the strongly anti-American public position he has taken, it is no more realistic to expect him to confront the Vietnamese Communists publicly than it is to expect him to take strong military action against them. It is not, however, unrealistic for us to endeavor to prevent Sihanouk from burning his bridges to the west and to convince him to press the Communists privately to reduce their use of Cambodian territory. In fact, the only method that offers any reasonable prospect of reducing enemy use of Cambodia is pressure by Sihanouk or action by him to obtain a substantial international presence. Military action by the United States in Cambodia runs a serious risk of driving Cambodia openly into collaboration with the Communists, thereby greatly expanding VC–NVN use of Cambodian territory, establishing a whole new front in the war, and increasing international condemnation of the United States as an aggressor. Diplomatic action is more likely to promote our interests than military action, and it involves much smaller risks, both military and political, to the United States.

C. U.S. Policy Towards Cambodia

There have been a few serious violations of Cambodian territory by U.S. forces, but it has been and remains agreed U.S. policy to avoid extending the Viet Nam war to Cambodia. Combat operations are not authorized in Cambodia except as necessary to suppress hostile fire from Cambodian territory and to preserve U.S. forces engaged on the South Vietnamese side of the border. Immediate pursuit of enemy ground forces into Cambodia is not otherwise permitted.

Despite these precautions there have been a number of incidents along the Cambodian frontier and NVA/VC use of Cambodian territory has been an increasing source of concern. The U.S. has protested the abuse of Cambodian neutrality through the Australian Embassy in Phnom Penh, and has attempted to persuade Sihanouk to discuss the problem directly. Sihanouk publicly rejected the U.S. initiative. The U.S. has also supported Canadian efforts to activate the ICC, but the Poles and Indians have blocked these initiatives. Aerial reconnaissance of Cambodian territory has been authorized to guard against a sudden enemy buildup in Cambodia and a limited number (5 per month) of Daniel Boone ground reconnaissance teams have been permitted to enter the remote northeast corner of the country where the Cambodian government has virtually no presence. Penetration to 20 kilometers has been author-ized, but the teams have not proceeded to that depth. The patrols are instructed to avoid contact with the civilian population and to avoid engagement with Cambodian forces except in self-defense. U.S. commanders in Viet Nam believe that these measures are insufficient and that new measures are required to inhibit NVA/VC exploitation of Cambodia.

D. Proposals for Military Actions in Cambodia

The Department of Defense has proposed an expansion of Daniel Boone operations in Cambodia that would (1) extend the operating area along the entire frontier from Laos to the Gulf of Siam; (2) authorize the infiltration and exfiltration of personnel by helicopter; and (3) increase the number of authorized missions from five to thirty each month. The twenty kilometer limitation on maximum penetration and other operating limitations now in effect would be retained.

This proposed revision of the Daniel Boone program would be fundamentally different from the small, covert operations now authorized in a remote corner of Cambodia. Increased frequency, operation in more populous areas, and the use of helicopters would greatly increase the risks of disclosure and of direct confrontation with Cambodian forces.

Moreover, expanded Daniel Boone operations in Cambodia cannot be viewed as an isolated step. Once authorization is granted for expanded military activities in Cambodia, the pressure for taking the next step—use of force against VC–NVN positions in Cambodia—would be very difficult to resist. We should be fully aware now of where the end of this road is likely to lead and not begin to go down it unless we are prepared to travel to the end.

From the legal point of view, Cambodia is not a party to the conflict in Viet Nam. It has not intervened in South Viet Nam and has not become a co-belligerent with North Viet Nam. It retains its status as a neutral. Abuse of Cambodian neutrality by NVA/VC forces does not automatically justify corresponding violations of Cambodian territorial integrity by U.S. or friendly forces. Such responsive violations can be justified only in cases where it may legitimately be claimed that the action is required in self-defense. Moreover, recourse must first be had to bilateral and multilateral diplomatic means of pacific settlement before reliance may be placed on the right of self-defense, except in cases where the act or threat being defended against arises suddenly and leaves no time for deliberation. When a threat develops and grows over a period of time, as in Cambodia, it is even more apparent that the threatened state is obligated to seek a pacific settlement before resorting to the use of force on the territory of a neutral and that it has had the opportunity to do so. Thus, Article 33 of the United Nations Charter obligates the “parties to any dispute, the continuation of which is likely to endanger the maintenance of international peace and security” to seek “first of all” a peaceful solution to the dispute. Article 37 provides that, should they fail to obtain a peaceful settlement, they are required to refer the dispute to the Security Council.

The extent and significance of NVA/VC use of Cambodian territory is uncertain, and our public documentation of a major enemy presence in Cambodia is thin, but there can be little doubt that enemy misuse of Cambodian territory and Cambodian failure to prevent such misuse constitute a dispute, “the continuation of which is likely to endanger the maintenance of international peace and security.” Under these circumstances, our obligation to attempt to settle the dispute by pacific means and, failing that, to take the dispute to the Security Council is clear.

Military force may legitimately be used by one state on the territory of another state in self-defense only when hostile actions threaten the first state in such a significant way that their suppression is not merely desirable but necessary and when such use of force is required to suppress them. In the absence of an impartial body that can effectively decide this question, it remains a matter of subjective judgment, but it is at least theoretically open to subsequent, impartial examination. With respect to Cambodia, it is far from clear that an impartial observer would decide that the demonstrable facts of its use by NVA/VC forces are sufficiently threatening to South Viet Nam and to our forces in South Viet Nam to justify direct military action based upon the right of self-defense. For the most part, Cambodia appears to be used as a source of supply, for temporary sanctuary, as a secondary infiltration route (at least in the past), and for hospital and rest areas. This uncertainty weakens the case for action in self-defense and thereby makes it even more important that all possibilities of pacific settlement be explored thoroughly before action is taken that can rest only on the basis of self-defense.

The two most extensive enemy base areas in Cambodia have been found in the northeast part of the country, but we have seen no reports of large troop concentrations in these areas. In our judgment, therefore, Daniel Boone operations should be authorized on a case-by-case basis and only in those situations where the specific dispositions of U.S. and friendly forces, reports of hostile activity in Cambodia, and other factors require cross-border ground reconnaissance to protect those forces from surprise attack by enemy forces believed to be massing in Cambodia. Great care must be taken to avoid disclosure and helicopters should not be utilized except in extraordinary circumstances.

The political cost of the disclosure of U.S. military operations in Cambodia would be enormous both in the international and the domestic context. Sympathies at home and abroad frequently would lie with Cambodia, which has managed to create an image of a small state struggling for survival amidst hostile neighbors. Public opinion would expect more convincing documentation of the necessity for self-defense in the case of a “neutral” than is normally required in respect of a belligerent. We may not have sufficient documentation of NVA/VC abuse of Cambodian territory for public use to overcome sympathies for Cambodia, and Sihanouk could make full use of the forum offered by the UN Security Council to play upon them. Further, many world leaders would regard the initiation of U.S. operations in Cambodia as a major escalation that would threaten to transform the conflict from a local war into general hostilities. Influential members of Congress would be outraged that the administration has taken steps to extend the conflict to another country without consulting the Congress. The result of such an incident could be sweeping new pressures to withdraw from Viet Nam. It is doubtful whether the possible military advantage that could be derived from the increment of information that would be obtained from expanded Daniel Boone operations justifies accepting that risk.

Costs of expanded U.S. military activity in Cambodia would also be exacted with respect to a future political settlement in Southeast Asia. Cambodia, and Prince Sihanouk, will, of necessity, play an important role in a peaceful Southeast Asia. We ought not now to take actions against Cambodia that will further alienate the Cambodians from the West and give them grounds for believing that their welfare depends on close ties to the Communist powers in Asia. We should be particularly careful not to initiate a “chain of eventsʼ which could affect political stability in Cambodia and open the way to Communist subversion. From a long-range viewpoint, the advantages of countering the threat posed by misuse of Cambodian territory must be balanced against the disadvantage of prejudicing the chances of a constructive role for Cambodia in the future political and economic development of Southeast Asia.

In view of the serious legal questions presented by these proposals and the high political costs that are anticipated, we believe that no decision should be taken to expand Daniel Boone operations in Cambodia until the offices concerned have had the opportunity to review (1) a detailed analysis of suspected enemy troop dispositions in Cambodia and the threat they pose to friendly forces in the border areas of South Viet Nam, and (2) a full statement of the public justification we would be able to make for our action in the very likely event of disclosure.

E. Alternatives

Ultimately, we cannot expect Sihanouk to take major steps to inhibit VC use of Cambodian territory unless he is persuaded that there will continue to be western influence in Southeast Asia and that this influence will not be hostile to Cambodia or to his government. The progress of the war in Viet Nam is the most important factor in this situation, but we should actively seek opportunities to demonstrate to Sihanouk our good intentions toward Cambodia, while at the same time making clear privately that large scale misuse of Cambodian territory cannot be tolerated. Obviously, that is a delicate task and one that could be rendered impossible if U.S. military action in Cambodia were revealed to the public while that effort is underway.

In the short run, the object of our diplomacy should be to (1) inform Sihanouk of the extent of NVA/VC use of Cambodian territory; (2) persuade him that failure to prevent such abuse, or to limit its growth, will create a greater risk for Cambodia than would remedial action; and (3) create sufficient international interest and concern to give Sihanouk a justification for acting, i.e., for putting pressure on the NVA/VC to restrain their activity in Cambodia, and/or for seeking an international presence to protect Cambodiaʼs frontiers.

We cannot expect Sihanouk to take such vigorous measures as would entail reprisals from the Communists, internal or external, but we can hope for a more active RKG presence in certain border areas that would tend to inhibit NVN/VC freedom of action. We can also hope for occasional sorties into border areas by the ICC, journalists and other fact-finders. These investigations could be useful to us if we can influence their location and timing. Even if little proof of VC activity is disclosed, a program of continuing investigations could inhibit enemy activity.

Accordingly, we recommend a program of continued diplomatic activity, public and private, calculated to (1) put maximum pressure on Sihanouk to take corrective action, (2) educate the public to the realities of the problem and (3) establish a better legal basis for future actions that may become necessary. In the interim, aerial reconnaissance of Cambodia and other intelligence measures (including Daniel Boone teams) should be continued at present levels to guard against a major build-up of enemy forces in Cambodia. Daniel Boone missions in areas other than the present operations area could be authorized on a case-by-case basis in those situations where, because of the specific disposition of friendly forces, reports of hostile activity in Cambodia, and other factors, it is believed that there may be an immediate serious threat to friendly forces from enemy forces on the Cambodian side of the frontier.

The diplomatic measures could include bilateral approaches to the Cambodian government, approaches to Sihanouk by influential leaders of third countries, a new high level approach to the Indian government to attempt to activate the ICC, and, depending on the strength of our public case, initiatives in the United Nations. The private approaches should include specific information on current VC/NVN misuse of Cambodian territory, a convincing statement of our good intentions toward Cambodia and the part we anticipate Cambodia will play in post-war Southeast Asia, and a gentle but firm warning that widespread and dangerous misuse of Cambodian territory cannot be tolerated.

Consideration should be given to the possibility of orchestrating pressures to compel Sihanouk to accept an outside mission with adequate freedom of movement that would include person(s) on whom we could rely. This maneuver could succeed only if Sihanouk were persuaded of the necessity to inhibit NVA/VC activity without a direct confrontation, and if he thought this device offered adequate cover. To this end the information available to the USG which can be declassified should be provided to Sihanouk. It is important that he be apprised of the seriousness with which the USG regards this situation and be given an opportunity to take some remedial action.

1. Source: Department of State, Central Files, POL 8 CAMB. Top Secret. Drafted by Mark B. Feldman and Aldrich of L/EA on September 9. A note on the source text indicates that it was seen by Bundy. Copies went to Harriman, Habib, and Lacey.
2. A “Memorandum of Law,” attached but not printed.
3. Document 199.