Foreign Relations of the United States, 1969–1976, Volume VI, Vietnam, January 1969–July 1970

268. Memorandum From John Holdridge of the Operations Staff of the National Security Council to the President’s Assistant for National Security Affairs (Kissinger)¹

Washington, April 28, 1970.

SUBJECT

• ONE Estimate of Hanoi’s Strategy in Cambodia

In response to my request the Office of National Estimates has prepared an assessment of Hanoi’s strategy in Cambodia.² The paper has not yet been cleared by Mr. Helms. The paper discusses the following topics:

I. Cambodia’s Role in the War

ONE states that Cambodia’s role in the war is vital to Hanoi for the following reasons:

• —If Hanoi could not use Cambodia for sanctuary, infiltration, and supplies, it would have to reassess its ability to continue the war in South Vietnam along present lines.
• —Hanoi’s immediate concern would be the loss of sanctuary areas, particularly opposite III Corps and IV Corps.
• —Hanoi also needs the base areas, which “provide the foundation upon which rest Communist expectations of maintaining an effective military/political apparatus in southern South Vietnam while the U.S. withdrawal proceeds.” The southern base areas have grown rapidly in the last two years.
• —The base structure also supports infiltration, handling an estimated 65,000 NVA personnel in 1969 (about 60 percent of total NVA infiltration that year).
• —Cambodia has long been an important source of supply, mainly rice. These supplies could probably be replaced.
• —The port of Sihanoukville is also important to Hanoi, enabling it to ship ordnance to its forces in South Vietnam. An estimated 2,000 tons of ordnance passed through Sihanoukville between October 1968 and January 1970, amounting to about one half of the Communist supply requirements during this period in II Corps, III Corps, and IV Corps. However, the loss of Sihanoukville would not be critical so long as overland trails are available.

II. Hanoi’s Assumptions

ONE believes that Hanoi now makes the following assumptions:

• —That there is little likelihood of renewed arms shipments through Sihanoukville.
• —That the U.S. will bomb the sanctuaries, bases, and routes in sparsely populated northeast Cambodia.
• —Most seriously, Hanoi fears allied plans regarding the frontier. A loss of effective control of the bases and the territory surrounding them would be a setback of critical proportions. It would have great psychological impact as well as military impact. It must appear imperative for Hanoi to hold the key bases in Cambodia and assure their security.
• —Hanoi probably assumes that the southern bases will be increasingly subject to allied encroachments, harassments, and limited air attacks. Hanoi does not fear Cambodia actions against those bases as much as ARVN attacks. It will be determined to show its readiness to try to hold key bases.

III. Anticipated Hanoi Actions

On the basis of this assessment, ONE believes Hanoi will take the following action:

• —To establish Communist controls along the border and further west to a depth consistent with military needs.³
• —To protect the bases against attacks, but not to drop them except as a result of major allied efforts.
• —If allied efforts are not sustained, to re-establish the bases and to change the entire character of the Cambodian sanctuary with new bases being developed in areas less accessible to the allies.
• —One cannot exclude the possibility of a more aggressive course such as a move against Phnom Penh, but it is uncertain that Hanoi would want to undertake such a risky and costly campaign. The thrust of Hanoi’s policy since mid-1968 has been to limit risks and conserve resources to concentrate on getting the U.S. out.
• —It is also possible that Hanoi will still try to make a deal with Lon Nol.
• —There may be a reduction in VC/NVA activities in Vietnam, particularly in the Delta, but there might be stepped up activity in I and II Corps when Communist capabilities are not likely to be affected and where Hanoi might want to draw our forces.
• —It is unlikely that Hanoi will move toward early negotiations.

IV. Conclusion

ONE’s conclusion is that current developments in Cambodia will bring at least temporary advantage to the non-Communist cause but that over the longer run the Communists will probably cope with the degradation of their sanctuary by reorganizing their supply lines, relocating their bases, and adjusting their combat tactics. In the meantime, Cambodia will have suffered a debilitating internal struggle, with large areas lost to Communists and “the seeds of eventual Communist control spread widely elsewhere in the country.”

1. Source: National Archives, Nixon Presidential Materials, NSC Files, Box 507, Country Files, Far East, Cambodia, Vol. IV, 24 April 1970–7 May 1970. Secret. Sent for information. Kissinger initialed this memorandum, and a stamped note reads: “HAK has seen.”
2. Not found.
3. On April 28 Holdridge sent Kissinger a second memorandum reviewing and listing North Vietnamese attacks in Cambodia beginning on April 13 and extending through April 24. Holdridge prefaced his annotated list with: “We are painfully aware of the difficulties in following the fighting in Cambodia because of inconsistent and fragmentary reporting.” The memorandum indicates Kissinger saw it. (National Archives, Nixon Presidential Materials, NSC Files, Box 507, Country Files, Far East, Cambodia, Vol. IV, 24 April 1970–7 May 1970)