251. Backchannel Message From the Ambassador to Vietnam (Bunker) to the President’s Assistant for National Security Affairs (Kissinger)1

169. Ref: WHS–0028.2

Consequences of Sihanouk’s Return.

Consequences of Sihanouk’s return, or another Communist victory, though they would depend somewhat on way in which this came about, would be profound not only in South Viet-Nam but also throughout all of Southeast Asia.
Sihanouk would return a Communist captive, shorn of any ability to play a neutralist role in Southeast Asian struggle. Lon Nol government and its principal supporters would presumably be liquidated or otherwise neutralized. Cambodia would become even more useful for Communist purposes and provide a base which North Vietnamese could exploit with even greater freedom to prosecute their objectives in South Viet-Nam.
There would be a longer or shorter period of confusion and turmoil in Cambodia following the takeover. The economic problems there would be increased, and demands would be put on Hanoi, China, and the Soviets for economic and military aid. This would put a premium on Sihanoukville as a port of entry.
We would assume VC/NVA would find it easier than in the past to recruit or impress manpower from the Vietnamese minority.
The restoration of Sihanouk or another Communist victory would give an enormous fillip to VC/NVN morale and propaganda. It would be treated as an American defeat.
It would have great impact in Laos, which would then have three Communist powers on its borders. Concern in Thailand would grow, and in Indonesia there would be increased pessimism about the future of the area.
With a Sihanouk restoration or Communist victory, the VC/NVA would be in a stronger position to carry on protracted warfare and they [Page 859] would be even less disposed than now to negotiate in Paris. Getting the VC/NVA out of Cambodia as part of a peace settlement would be more difficult.
A hostile Cambodia would force a reexamination of the speed of the Vietnamization process by both the GVN and the US, and might counsel extending the period of American involvement in South Viet-Nam.
While Thieu has the impression that the return of Sihanouk would be viewed by Vietnamese as a restoration of the status quo, we doubt that the consequences would be that simple. Not to be ruled out is the possibility that a development in Cambodia so unfavorable to Vietnamese prospects could create discouragement in South Viet-Nam political and military circles and there could be a serious let down in South Viet-Nam. While most Vietnamese military leaders have not wanted to probe too deeply, too widely, or commit too many forces in cross border operations, people like Ky can be expected to criticize the US and possibly Thieu for failure to take advantage of what Ky called “a golden opportunity.” In such an event, and coming on heels of the 150,000 redeployment target, USGVN relations might be put under some stress. Just as the loss of Laos would produce shock waves in South Viet-Nam, there would be even greater shock waves if Cambodia fell to Communist control or to a Sihanouk who was their captive.
One of the major likely consequences would be a prolongation and, over time, a possible intensification of the war, especially in the southern part of Viet-Nam. Whether this prospect would be met with renewed GVN determination would depend in part on the ability of South Vietnamese political and military leadership to damp down the criticism of the US and possibly of Thieu.
We do not believe that the development of a larger threat across the border would increase the interest of the GVN in seeking negotiated solutions through wider concessions, but rather would harden their insistence on a continued and indefinite US presence. At the same time it might encourage more of the dissident political elements within South Viet-Nam to advocate concessions and compromises, increasing political strains in the South.
Thus I would conclude that the return of Sihanouk or a Communist victory in Cambodia would be a serious setback. It would add to our problems and those of the GVN; it would complicate obtaining a reasonable political settlement for Viet-Nam; it would make more difficult obtaining agreement on mutual withdrawal from Viet-Nam, Cambodia, and Laos; and it might force US into a long term and costly large-scale presence in Viet-Nam. Every prudent step should be taken to reduce its possibility.
The following measures are submitted for consideration:
Increase worldwide psychological warfare campaign through overt and covert assets to call attention to North Vietnamese aggression in Cambodia. Attention should be called to the Communist interdiction of Mekong River as international waterway. This campaign should emphasize that Hanoi’s hostile actions in Cambodia threaten the conflict in Southeast Asia.
Undertake diplomatic effort through the UN, ICC, and any other grouping of nations which can be used to help stabilize the situation in Cambodia. In recommending this course of action we are not unmindful of previous attempts to harness this approach which have been less than productive.
Implement presently agreed upon indirect arms assistance efforts to the Cambodians with maximum speed, realizing that this gesture in the short term is of more psychological than military value.
Encourage and actively guide as appropriate the current efforts of the GVN to establish direct contact between Saigon and the Lon Nol government.
Expand military assistance to the Lon Nol government through indirect channels to include communications equipment, heave weapons, aircraft spare parts and limited number of T–38 [T–28] aircraft.
Airlift three battalions of Khmer Serei and one battalion of KKK oriented CIDG troops into Phnom Penh after conducting appropriate coordination with the Lon Nol government. These four battalions are combat-ready units. Their movement to Phnom Penh could be carried out by GVN aircraft. These troops are equipped however with M–16’s and other American equipment, thus their deployment poses some follow-on logistics problems, none of which are insurmountable. We have indications these troops would be willing to go to Cambodia. There are also 3,000 recruits of Cambodian descent in the CIDG training pipeline. Thieu told me and informed General Vien that Cambodians should be released if they want to go. There are reports that Lon Nol would be willing to receive and integrate this type of manpower into his own forces.
Increase the number of short term ARVN cross border operations in shallow penetrations designed to increase VC/NVA concern about the security of their base and logistics areas.
Maintain military pressure on North Vietnamese forces in northern and southern Laos and encourage the Thai government to send infantry battalions to the Sam Tong/Long Tieng salient.
Provide US gunship, artillery and TACAIR support to ARVN forces operating in Cambodia against significant VC/NVA targets.
Mount selective and carefully targeted combined US/GVN military operations against high payoff targets in Cambodia. One of these might be against COSVN headquarters.
Mount naval operations with GVN resources to open the Mekong River as an international waterway if VC/NVA forces continue to interdict the river. This should be undertaken only after the appropriate psychological warfare stage setting has been achieved via actions outlined in recommendation A.
Update and prepare for prompt implementation, a scenario and a contingency plan which would utilize US/GVN naval resources to quarantine the port of Sihanoukville immediately after our intent to impose such a quarantine was appropriately signalled to interested nations.
Apply appropriate military force against carefully selected targets of tactical or strategic importance located in the southern and western portions of North Viet-Nam along the Lao/North Vietnamese border.
  1. Source: National Archives, Nixon Presidential Materials, NSC Files, Box 410, Backchannel Messages, Southeast Asia, 1970. Top Secret; Sensitive; Eyes Only. Received at the White House Situation Room at 9:41 a.m. Washington time.
  2. In White House telegram WHS0028, April 21, Kissinger requested, on behalf of the President for the NSC meeting on April 22, Bunker’s and Abrams’ candid views on the “military/political/psychological consequences of a Sihanouk return or another Communist victory in Cambodia.” (Ibid.)