Weapons of Mass Destruction

Washington, D.C., June 3, 2025 - The Trump administration’s intention to acquire Greenland, including possibly by force, has put a focus on the history of its strategic interest to U.S. policymakers. Today, the National Security Archive publishes the first of a two-part declassified document collection on the U.S. role in Greenland during the middle years of the Cold War, covering the decisions that led to the secret deployment of U.S.

Washington, D.C., January 23, 2025 - Today, the National Security Archive publishes newly declassified information on a secret mid-1960s project in which a handful of young physicists at Lawrence Livermore Laboratory produced a design for a “credible nuclear weapon” based only on unclassified, open-source information and in just three years. One of the participants described the experiment as “truly a do-it-yourself project,” according to one of the recently declassified records.

Washington, D.C., August 8, 2024 – On the week of the 79th commemoration of the U.S. atomic bombings of Hiroshima and Nagasaki, Japan, the National Security Archive today publishes a fascinating new collection of papers from the office files of Leslie Groves, the director of the Manhattan Project, the U.S. effort during World War II to develop and produce the world’s first nuclear weapons.

Washington, D.C., July 16, 2024 - On 16 July 1945, 79 years ago, the United States, under the Manhattan Project, staged the first test of a nuclear weapon in the New Mexican desert. The first trial of a plutonium implosion weapon, the explosion on the ground produced radioactive fallout contaminating over 1,100 square miles of the state, although some debris spread as far north as Canada.

Washington, D.C., February 29, 2024 - Seventy years ago, on 1 March 1954 (28 February in Washington), the U.S. government detonated a thermonuclear weapon, code-named “Shrimp,” on Bikini Atoll in the Marshall Islands in what turned out to be the largest nuclear test in U.S. history. The Bravo detonation in the Castle test series had an explosive yield of 15 megatons—1,000 times that of the weapon that destroyed Hiroshima and nearly three times the six megatons that its planners estimated.

Washington, D.C., October 26, 2023 - In early August 1977, Communist Party General Secretary Leonid Brezhnev wrote to President Jimmy Carter to inform him that the Soviet Union had detected a nuclear weapons test site in South Africa and to ask that the U.S. and other governments take “energetic efforts” to prevent the emergence of a new nuclear weapons state. Within days, the U.S.

Washington, D.C., September 21, 2023 – The Reagan administration rejected an international agreement on humanitarian laws of war—Additional Protocol I to the 1949 Geneva Conventions—due to insurmountable objections from the Pentagon and the belief that it favored terrorists, according to a collection of declassified documents posted today by the National Security Archive.

Washington, D.C., June 6, 2023 - U.S. officials and NATO allies feared that international talks meant to strengthen the protection of civilians during conflicts could lead to a ban on the use of nuclear weapons, according to a September 1975 memorandum by the Pentagon’s Joint Staff posted today by the National Security Archive. Published as part of a new Electronic Briefing Book on the negotiations that produced Additional Protocol I to the 1949 Geneva Conventions, the Defense Department memo reveals some of the concerns that underlay the initial U.S.

Washington, D.C., March 20, 2023 -The declassified Air Force film shows the crew of a U.S. B-52 bomber reaching its “Positive Control” (“fail safe”) point on the way to its target in the Soviet Union. But instead of turning around as usual, they get an order to proceed to their assigned objective. Having received and authenticated a “Go Code” message from U.S. Strategic Air Command (SAC), the pilot announces, “We’re going in,” navigating the aircraft in low over mountains, lakes, fields, and forests to avoid Soviet air defenses.

Washington, D.C., November 18, 2022 - A top safety official at a U.S. nuclear weapons lab wrote that “the public must be encouraged to realize that risks [of an unintentional nuclear detonation] cannot be zero and cannot ever be really known,” according to a newly released 2001 history of U.S. efforts to mitigate the dangers of accidental or unsanctioned weapons detonations. Declassified in response to a Freedom of Information Act (FOIA) request by the National Security Archive, the history, written by former Sandia National Laboratories official William L.