243. Memorandum From the Director of the Bureau of Intelligence and Research (Hilsman) to the Secretary of State1


  • Reports on Increased Communist Infiltration into South Vietnam from Laos


In accordance with your request we have examined the available intelligence information related to recent reports on increased Communist infiltration into South Vietnam.


Communist infiltration into South Vietnam appears to have increased since May 1962, but it is not necessarily related to current developments in Laos. Althou,2h the magnitude of this movement is difficult to assess, it is believed to involve largely well-trained armed cadres and key officials rather than armed units. As in the past, moreover, the movement is confined principally to South Vietnamese (Annamites and Cochinchinese), trained in North Vietnam, rather than North Vietnamese (Tonkinese) who constitute the bulk of the DRV forces now serving in Laos.

Communist infiltration will continue to remain a problem in South Vietnam. The DRV has the capability of stepping up infiltration over the present level, if circumstances warrant, with no great difficulty and relatively little danger of detection.

American press despatches from Saigon continue to report a sharp step-up in Communist infiltration into South Vietnam from southern Laos. The latest such report, on July 14, 1962, quoted a “US civilian observer” (who was allegedly quoting a “US intelligence adviser”) as stating that 2,500 to 3,000 Communists “have been streaming like water through a sieve across the border from Laos into South Vietnam” during the past five-week period. Earlier this month, American newsmen reported that US sources agreed with South Vietnamese intelligence estimates that as many as 8,000 to 9,000 Communists may have been infiltrated from Laos. US sources were also quoted as speculating that, “with the pro-Communists firmly in control of the Lao infiltration routes under the new coalition government,” North Vietnamese may be moving more of their estimated 10,000 troops in Laos into South Vietnam.

[Page 522]

US Field Assessment

The US Military Assistance Command in Vietnam (MACV) has recently concluded that Communist infiltration into South Vietnam has increased significantly since early May 1962. On June 29, MACV reported that probably 800-1,000 Communists had been infiltrated during May and another 800 during the first three weeks of June.2 (MACV infiltration assessments for previous periods are 500-1,000 per month from June through November 1961, and 100-200 per month from December 1961 through Apri1 1962.) MACV also reported that the formation of a coalition government in Laos might prompt the North Vietnamese regime to step up infiltration further.

On July 5, Embassy Saigon reported that the MACV assessment was based largely on unconfirmed information, that forces infiltrated were mostly well-trained cadres and key officials, and that the infiltration pattern was not related to the formation of a coalition government in Laos.3

Recent Increase in Infiltration Evident

Despite the paucity of confirmed reports, the MACV assessment of an increase in the infiltration rate appears valid. First, the increase in the number of unconfirmed reports on infiltration during the past two months cannot be ignored. Second, there is at least one confirmed report of the crossing of a 200-man Communist unit into Kontum province from Laos on May 6-7, 1962. Third, Communist control of the border area in southern Laos has improved. And fourth, the increased aggressiveness and mobility of the South Vietnamese Government forces has begun to hurt the Viet Cong, and the North Vietnamese authorities may now feel that they must quickly strengthen the position of the Viet Cong.

It is difficult, however, to accept the reliability of the statistics—and therefore the magnitude of the increase—in MACVʼs assessment Virtually all such information comes from Vietnamese intelligence sources which tend to overstate the infiltration factor. Moreover, South Vietnamese patrolling of the Laos frontier, which could constitute an important means of collecting or confirming intelligence on the Viet Cong in that area, has been very limited.

Laos Developments Probably Unrelated

It does not necessarily follow, as apparently some American press and even US military (as well as official Vietnamese) sources suggest that the step-up in infiltration is related to recent developments in [Page 523] Laos which have resulted in the freeing of Vietnamese Communist forces there for use in South Vietnam. The Communist forces infiltrated into South Vietnam are believed to be almost entirely Cochinchinese and Annamites, the same stock as the people who constitute the bulk of the South Vietnamese peasantry; on the other hand, the Vietnamese Communist forces serving in Laos are largely Tonkinese. The deployment of Vietnamese Communist armed forces in Laos to the South Vietnamese theater, therefore, would go counter to a basic Communist tactic which has heretofore proved effective in South Vietnam in building up an apparatus from personnel native to this area, familiar with local conditions and terrain, and closely identified with the local populace.

There are other reasons which do not favor the deployment of Vietnamese Communist forces fighting in Laos into South Vietnam. There is a certain amount of mutual distrust among the Annamites, Cochinchinese, and Tonkinese, and some problems in integrating these forces could be expected. Moreover, the capture of Tonkinese personnel would destroy North Vietnamʼs propaganda claim that the Viet Cong insurgency is entirely a movement of the South Vietnamese people.


On the basis of available intelligence information, we conclude that:

there has probably been an increase in the infiltration of Communist personnel into South Vietnam during the past two months;
it is difficult to assess the magnitude of this movement;
the increase in infiltration probably is not related to recent developments in Laos;
it appears unlikely that North Vietnamese or Pathet Lao forces in Laos would be committed to South Vietnam at this time; and
North Vietnam has the capacity to step up infiltration further, if the situation warrants, with relatively little detection and no great difficulty.

  1. Source: Department of State, Central Files, 751K.00/7-1662. Secret; Noforn. Signed by Hilsman and sent through S/S.
  2. Not further identified.
  3. Transmitted in telegram 15 from Saigon; Department of State, Central Files 751K.00/7-562.