140. Memorandum From President Johnson to Secretary of Defense McNamara and the Chairman of the Atomic Energy Commission (Seaborg)1

The National Nuclear Test Program transmitted by your joint letter of February 25, 1966,2 has been reviewed by the Executive Office staff. I wish to confirm that it is most important that we retain a test readiness posture and maintain an active plan to resume testing should it be necessary.

I note that the Program is sufficiently broad in scope as to provide maximum flexibility of response in the event we should have need to resume testing in any of the environments now prohibited by the limited test ban treaty. This approach is sound, and its flexibility should continue to characterize our planning.

The Program should be periodically reviewed to insure that it takes into account the advances made in our underground test program and the other research and development work at the laboratories and within the Department of the Defense. Periodically this Program needs updating and any significant changes that occur in the Program should be brought to my attention.

Lyndon B. Johnson
  1. Source: Johnson Library, National Security File, Subject File, Nuclear Testing—National Nuclear Test Program, Vol. I, Box 31. Secret.
  2. The letter under reference transmitted “The National Nuclear Test Program, First Revision—January 1, 1966.” (Washington National Records Center, RG 330, OSD/AE Files: FRC 72 A 4120, 93. National Nuclear Test Readiness Program (1964-66) The revision was requested by a memorandum from Bundy to McNamara and Seaborg, May 25, 1965. (Ibid.)