During the period April 1952–April 1954, the United States conducted four series of tests of nuclear and thermonuclear weapons.
The first series, designated Tumbler-Snapper, was conducted at the Yucca Flat test site in Nevada between April 1 and June 5, 1952. The tests involved one-kiloton atomic devices set off both from towers and by air drops. The objective of these tests was to [Page 882] learn more about the dust “sponge” effect and the relationship of dust to radiation. (Memorandum for the files by R. Gordon Arneson, Special Assistant to the Secretary of State for Atomic Energy Affairs, January 22, 1952, G/PM files, lot 68 D 349, “Nuclear Testing, Tumbler-Snapper”)
The second series took place at Eniwetok Atoll in the Pacific and involved the first thermonuclear or “H-Bomb” detonation. No formal announcement was made of these two tests, which took place on October 31 and November 15, 1952, under the designation Ivy, and security restrictions were maximized. (Rodney L. Southwick, Assistant Chief of the Public Information Service, United States Atomic Energy Commission, to Arneson, December 10, 1952, G/PM files, lot 68 D 349, “Nuclear Testing Ivy”)
The third series of tests was again conducted at Yucca Flat between March 17 and April 6, 1953, and was designated Upshot-Knothole. Limited public access in the form of admission of state and municipal civil defense directors and representatives was permitted on a “one-shot basis” as was limited media representation. The purpose of these tests was to measure and assess nuclear blast effects upon dwellings, shelters, automobiles, etc. Only atomic devices were detonated. (Memorandum by S. Everett Gleason, Deputy Executive Secretary of the National Security Council to the Secretary of State and others, February 21, 1953, G/PM files, lot 68 D 349, “Nuclear Testing, Upshot-Knothole”)
The fourth and final series of tests again took place at Eniwetok between February 28 and May 5, 1954 under the code designation Castle. The purpose of these tests was to further perfect the thermonuclear weapons first tested during the Ivy shots of November 1952. Public attention quickly focused on these tests as a result of the radiation poisoning of crew members of the Japanese fishing boat Fukuryu Maru which had strayed too close to the test site area. For documentation on public concern in Japan, the Marshall Islands, and the United States over possible widespread contamination of the seas and atmosphere as a result of nuclear testing, and on the statements by United States Atomic Energy Commission Chairman Lewis L. Strauss, Secretary Dulles, and United States Representative to the United Nations, Henry Cabot Lodge, Jr., justifying the need for testing and minimizing the widespread risks, see Department of State Bulletin, March 29, 1954, page 466; April 12, 1954, pages 548–549; April 19, 1954, pages 598–599; June 7, 1954, pages 886–887; and June 14, 1954, pages 926–928.
Department of State files contain only the most limited and fragmentary information concerning the above tests. Numerous documents are missing from the G/PM files cited above as well as from the S/AE files, lot 68 D 358, with only the covering sheets and [Page 883] memoranda available to indicate their subject and, occasionally, to provide a brief summary of content. Further information on the United States nuclear and thermonuclear testing programs in 1952–1954 is in Hewlett and Duncan, Atomic Shield, page 673; and in Samuel Glasstone, editor, The Effects of Nuclear Weapons (Washington, United States Atomic Energy Commission, April 1962), pages 672–673.
During March and April 1954, as part of the follow-up campaign to President Eisenhower’s “Atoms for Peace” speech before the United Nations on December 8, 1953, the United States Government released to the public an unclassified motion picture account of the Ivy thermonuclear test series of October 31 and November 15, 1952. For information on the events leading to this decision, see the progress report of the Working Group on Implementation of the President’s United Nations Speech, April 30, 1954, page 1403.