Foreign Relations of the United States, 1964–1968, Volume XXVIII, Laos

249. Telegram From the Embassy in Laos to the Department of State¹

Vientiane, September 11, 1966, 0715Z.

1447. Joint Embassy/ARMA/CAS message. Subject: North Vietnamese order of battle in Laos. Ref: A. CINCPAC 180030Z Aug (notal).² B. FOV 9190.³ C. AmEmb Vtn 641/030521Z Aug.⁴

1. This is a preliminary response to Ref A based on information provided by CAS Vientiane. Mission plans conduct in very near future review of enemy OB in Laos and will furnish addressees with results of this review. We believe that this review will be facilitated as result increased emphasis on south Laos [less than 1 line of source text not declassified]. Intelligence produced by this effort should enable us to make hard estimate through collection all source data whereas previous estimates for south Laos had minimal input from controlled assets.

2. CAS OB estimate for 1 July 1965 reflected two possible NVNA infantry bns with Lao troops, 4,525 NVNA troops attached to PL battalions in platoon to company strength (PL/NVNA), and 700 NVNA troops attached to PL battalions as advisors (PL/NVNA), giving total 5,825 probable troops in Laos. In addition CAS estimates that there were about 10,000 engineers (including coolie labor) and about 3,000 NVNA personnel in support activities such as medical, supply, transportation, signal, command, etc., which gave total 18,325 NVNA personnel in Laos as of 1 July 1965.

3. OB estimates for 1 July 1966 reflected 19 probably NVNA infantry bns with strength of 7,435 troops, 4,525 NVNA troops attached to PL battalions from platoon to company strength and 680 NVNA troops attached to PL battalions as advisors. Same estimate reflected 21,000 engineers (including coolies) and about 7,000 in support activities which gave total of 42,265 NVNA personnel in Laos as of 1 July 1966.

4. Comparison of 1 July 1965 and 1 July 1966 figures indicate increase of 23,430 NVNA personnel in Laos during that one year period.

5. Eighty percent of the infantry (NVNA) (PL/NVNA) and (PL/NVN) increase attributable to influx of new personnel into Laos from North Vietnam. A 100 percent increase in engineer personnel (including coolies) reflected movement new personnel into Laos in conjunction with 50 percent increase engineer effort at road building maintenance during the past nine months.

6. Support personnel in Laos increased over 100 percent in connection with increased activity in infantry and engineer fields.

7. Above figures considered as confirmed within CAS’s OB accept-ance criteria (para 8) and as such reflect reporting from human sources in areas where there is continuing coverage in depth. As indicated paras 5 and 6, therefore, major portion above increase reflects actual movement new NVNA personnel and units into Laos including normal replacement filler troops for KIA/WIA.

8. Determination if new enemy troops are replacements for losses, normal rotation or new units made only after lengthy analysis of several months traffic. On occasion, however, such as NVN prisoner taken Na Khang Battle past February, reported in FOV 8942,⁵ CAS obtained firsthand information on movement new NVN units into Laos. Otherwise professional analysis of reports using well established OB techniques; experience of OB analyst and common sense are blended in making judgements on which troops reflect casualty rotation replacements vis-à-vis troops belonging to new unit. For example, four thousand troops reported Ref B not killed in one fell swoop but over period Nov 65–Jun 66, prior to, throughout and after which period CAS continues receive reports of manpower conscription throughout Laos and of troops arriving in Laos from NVN.

9. Ref A, however, also considered areas not covered in depth by CAS human sources and reflected use of sources such as aerial photography, special intelligence and refugee interrogations to make estimate of enemy strength in those areas. This estimate primarily an extension of enemy strength identified in well covered areas of Laos and as such CAS considers majority enemy personnel in areas where estimates were made to also reflect new bodies from NVN.

10. CAS conclusion: at least two-thirds of NVN increase mentioned Ref B attributable actual movement new personnel into Laos. Increase in PL strength (Ref B) on other hand reflects almost exclusively bookkeeping changes based on refinement of estimates made possible by receipt additional and more detailed information.

11. ARMA believes that there is conclusive evidence of a substantial NVA buildup during period Jul 65–66. ARMA also believes that there is evidence of a diminution in PL combat and combat support activity which may to some extent offset the NVA increase as well as reduce CAS’s estimate of PL strength. ARMA not convinced (A) that enemy losses (KIA, WIA, and rallies) are adequately reflected, (B) that enemy effective unit strengths are as high as CAS estimates, nor (C) that enemy unit designations are not inflated by deception tactics as practiced in RVN. These reservations concerning accuracy of existing estimates are being fully examined in ARMA study now under way to which CAS is contributing.

Sullivan

1. Source: Department of State, Central Files, POL 27 LAOS. Secret.
2. Dated August 18. (Ibid., POL 27 VIET S)
3. Not further identified.
4. Document 244.
5. Not further identified.