80. Memorandum From the Joint Chiefs of Staff to the Secretary of Defense (McNamara)1



  • Defoliation—Operational Evaluation
Reference is made to JCSM-738-62, dated 28 September 1962,2 Subject: “Review and Operational Evaluation of Defoliation Program in South Vietnam.” In this memorandum, the Joint Chiefs of Staff concurred in a conclusion forwarded by CINCPAC which stated essentially:

Potential effectiveness of defoliation was overestimated, particularly in those areas of mixed vegetation, but it was effective in mangrove areas.


On the basis of the more recent information contained in the Appendix3 hereto, evaluation of additional evidence indicates the desirability of revision of the initial conclusions. Whereas the initial test [Page 207] defoliation operations against mangrove forests in January-March 1962 gave satisfactory results, excellent results were obtained in the defoliation operations against mangrove forests in September-October 1962, by using increased quantities of herbicide per acre and a larger droplet size. Additionally, subsequent operations indicate that the results of using herbicides in test defoliation operations conducted prior to March 1962 in the Republic of Vietnam against evergreen and scrub forest were not conclusive because:

The tests were conducted during the dormant season for the above types of vegetation.
An insufficient quantity of herbicide per acre was used.
The droplet size was too small.

Based on the technical evaluation of the results attained in the January-March 1962 tests against evergreen and scrub forests and the increase in effectiveness obtained against mangrove areas, as stated above, there is now a good reason to conclude that herbicides, if used during the growing season in the proper quantity per acre and in a correct droplet size, would be effective against evergreen and scrub forests.

The letter4 from the Commander, United States Military Assistance Command, Vietnam, in the Appendix hereto should be of interest to the Advanced Research Projects Agency.

For the Joint Chiefs of Staff:

A. H. Manhart5
Major General, USA
Deputy Director, Joint Staff
  1. Source: Washington National Records Center, RG 330, OSD Files: FRC 66 A 3542, 370.64 2 Feb. Vietnam 1963. Secret.
  2. Not printed. (Ibid.)
  3. Not found attached.
  4. Not found.
  5. Printed from a copy that bears this stamped signature.