147. Memorandum From Secretary of Defense McNamara to President Johnson1

General Westmoreland has requested a reaffirmation of his authority to use standard riot control munitions in certain specified combat situations in South Vietnam and Ambassador Lodge has supported his request. This authority would extend only to lacrimatory agents (tear gas) known as CS and CN. Use of nausea-producing agents DM and CN-DM would not be authorized.

The agents would be used primarily to clear tunnels, caves, and underground shelters in cases where their use will lead to far fewer casualties and less loss of life than would the combat alternatives which involve high explosive or flame munitions. Of particular importance would be the reduction in casualties to civilians who are inevitably mingled with hostile military elements as the result of VC tactics.

I agree with General Westmoreland that the use of these riot control agents far outweighs disadvantages that may accrue; in fact there is every indication that we may be in for censure if civilian casualties should accrue because we didn't use tear gas. The disadvantages to which I refer are the likelihood of some sharp international criticism, spurred by Communist propaganda, of the U.S. Government authorizing the employment of what will inevitably be called “poison gas”.

Unless you indicate otherwise I will reaffirm to General Wheeler the current national approval for the use of the riot control agents CS and CN under the combat conditions described above.

Secretary Rusk concurs in this recommendation.

If you approve, the Department of State will send a message to all posts informing them of the decision and providing public affairs guidance.

Robert S. McNamara
  1. Source: Johnson Library, National Security File, Memos to the President, McGeorge Bundy, Vol. XV. Secret.