On August 5, 1963, foreign ministers from the United States, Soviet Union, and United Kingdom signed the Limited Nuclear Test Ban Treaty in Moscow, prohibiting nuclear tests in the atmosphere, outer space, and underwater. Coming less than a year after the Cuban Missile Crisis brought the world to the brink of nuclear war, the treaty marked the first major arms control agreement of the Cold War.
The treaty's roots lay in genuine public fear. By the early 1960s, scientists had documented rising levels of Strontium-90 in milk and children's teeth worldwide, fallout from more than 500 atmospheric nuclear tests conducted since 1945. Nobel laureate Linus Pauling and other scientists had campaigned for years for a ban, warning of genetic damage and rising cancer rates from radioactive contamination drifting across the globe.
The Cuban Missile Crisis of October 1962 transformed the political will behind these warnings. Having stared into the abyss, Kennedy and Khrushchev both sought ways to reduce tension without appearing weak to domestic hawks. A test ban limited to atmospheric, space, and underwater tests—leaving underground testing permitted—offered a face-saving middle path that verification technology of the era could actually monitor.
Secretary of State Dean Rusk, Soviet Foreign Minister Andrei Gromyko, and British Foreign Secretary Lord Home signed the document in the Kremlin's ornate Catherine Hall. Within months, over 100 nations had joined. France and China, both pursuing independent nuclear arsenals, notably refused to sign, and both continued atmospheric testing for years afterward.