134. Editorial Note
A June 6, 1966, letter from Glenn T. Seaborg to President Johnson submitted for approval the underground nuclear test program for fiscal year 1967, designated Latchkey, and a detailed plan for the first quarter (July-September), Latchkey I. The proposed program consisted of approximately 56 tests, including 38-42 weapons development and 7-9 Plowshare tests (including the deferred Cabriolet), sponsored by the Atomic Energy Commission, and 1 test detection and 7 weapons effects tests, sponsored by the Department of Defense. (Johnson Library, National Security File, Subject File, Nuclear Testing, U.S. Testing Program, Latchkey Series, Vol. V, FY 1967, Box 28)
A memorandum from Rostow to the President, June 25, stated that the Review Committee on Underground Tests recommended approval of the program for fiscal year 1967, subject to the following reservations (with DOD and AEC concurrence): cratering experiments and tests [Page 328] executed off the Nevada Test Site required specific Presidential approval; and the large-yield (600 kt) [Greeley] test for the first quarter was subject to Dr. Hornig’s review of test procedures and safety precautions. The President’s approval line on this memorandum was checked. (Johnson Library, National Security File, Subject File, Nuclear Testing, U.S. Testing Program, Latchkey Series, Vol. V, FY 1967, Box 28) Rostow informed Seaborg of this decision by memorandum of June 27. (Ibid.)
Rostow’s November 3 memorandum to the President stated that the Review Committee on Underground Tests recommended approval of the AEC tests program for November-December, the remaining months of Latchkey II, including the large-yield Greeley test, but it withheld authorization of Cabriolet pending the President’s decision on that event. The President’s approval line on this memorandum was checked. (Ibid.) A January 9, 1967, memorandum from Rostow to the President stating that the Review Committee on Underground Nuclear Tests had no objection to the AEC test program for the third quarter (January-March), recommended approval of Latchkey III, consisting of 14 tests including Cabriolet. That test, however, required issuance of a prior public explanatory statement, coordinated by the Atomic Energy Commission and the Under Secretary of State, with Department of State, ACDA, DOD, and White House clearances before release. The President’s approval line on the memorandum was checked. (Ibid.) Rostow informed Seaborg of this approval by memorandum, January 11, 1967. (Ibid.)
Ultimately the United States Government conducted 38 tests, including Greeley (870 kt), but not Cabriolet in the Latchkey series. (United States Nuclear Tests, July 1945 through September 1992, pages 28-30) Further documentation on the Latchkey series is in the Johnson Library, National Security File, Subject File, Nuclear Testing, U.S. Testing Program, Latchkey Series, Vol. V, FY 1967, Box 28 and in Department of State, S/S-RD Files: Lot 71 D 171.
A summary history of the test series is U.S. Defense Nuclear Agency, Operations Flintlock and Latchkey: Events—Red Hot, Pin Stripe, Discus Thrower, Pile Driver, Double Play, New Point, Midi Mist, 5 March 1966-26 June 1967 (DNA 6321F, 1984).