259. Letter From Secretary of Defense McNamara to Secretary of State Rusk 1

Dear Dean:

By message of 16 August 1966 (Saigonʼs 3601),2 Ambassador Lodge raised the question of the possible extension of defoliation operations [Page 700] into the DMZ and requested the views of the Departments of State and Defense on the desirability of doing so.

The Joint Chiefs of Staff have concluded that, from a military standpoint, defoliation of areas in SVN within and near the DMZ is highly desirable and should be undertaken. I agree with this position.

As you are aware, Viet Cong (VC) and North Vietnamese Army (NVA) forces have been exploiting the combination of remoteness and heavy vegetation found in the DMZ to their own purposes and advantage. This is particularly true in the western sector. The seriousness of NVA/VC use of the zone is illustrated by the recent introduction of the 324B Division of the NVA directly across the zone into SVN where the force now confronts GVN, US and other friendly forces in combat. Intelligence indicates that the communists are resupplying the units recently infiltrated into South Vietnamʼs Quang Tri Province through the DMZ and are building a supply base in the zone for future operations.

Defoliation in the southern portion of the DMZ may have political as well as definite military advantages. Such operations are defensive in nature and would assist the efforts of the ICC and all who seek actual demilitarization of the zone.

Defoliation has been conducted in SVN since 1961 and in Laos since 1965. Such operations continue routinely today. In my opinion, the political risks of defoliation in and near the DMZ should be less than the predictable military risks of failure on our part to take all reasonable measures to deny the communists continued use of the DMZ. Since it takes up to three months for the jungle cover to fall after spraying, this matter is one which requires early attention.

Current authority for defoliation within SVN was delegated to the American Ambassador Saigon and COMUSMACV after review by the highest authority in May 1963. Extension of this authority to include the southern portion of the DMZ would seem to be appropriate under current circumstances. If you agree, I would appreciate your releasing the required instruction essentially as contained in the attached draft joint State/Defense message.3


  1. Source: Johnson Library, National Security File, Country File, Vietnam, vol. LX. Secret.
  2. Not printed. (Department of State, Central Files, POL 27–10 VIET S)
  3. Attached but not printed. Rusk concurred in a letter of November 18 to McNamara, stating: “While I can foresee some unfavorable political reaction to these operations, I believe the reaction would be manageable as long as we avoid defoliating any area of North Vietnam.” Defoliation operations in the southern sector of the DMZ were authorized in telegram 91707 to Saigon, November 26. Ruskʼs letter is quoted and telegram 91707 is cited in JCS telegram 1752, December 19. (Johnson Library, National Security File, Country File, Vietnam, vol. LXII)