Much of the stimulus for the treaty was increasing public unease about radioactive fallout as a result of above-ground or underwater nuclear testing, particularly given the increasing power of nuclear devices, as well as concern about the general environmental damage caused by testing.
In 1954, the US Castle Bravo test at Bikini Atoll (part of Operation Castle) had a yield of 15 megatons of TNT, more than doubling the expected yield.
On , the Soviet Union proposed a test ban before the UN Disarmament Commission's "Committee of Five" (Britain, Canada, France, the Soviet Union, and the US).
but his interest in international controls was echoed in the 1946 Acheson–Lilienthal Report, which had been commissioned by President Harry S.
Truman to help construct US nuclear weapons policy. Robert Oppenheimer, who had led Los Alamos National Laboratory during the Manhattan Project, exerted significant influence over the report, particularly in its recommendation of an international body that would control production of and research on the world's supply of uranium and thorium.
The Castle Bravo test resulted in the worst radiological event in US history as radioactive particles spread over more than 11,000 square kilometers (4,200 sq mi), affected inhabited areas (including Rongelap Atoll and Utirik Atoll), and sickened Japanese fishermen aboard the Lucky Dragon upon whom "ashes of death" had rained.
In 1961, the Soviet Union tested the Tsar Bomba, which had a yield of 50 megatons and remains the most powerful man-made explosion in history, though due to a highly efficient detonation fallout was relatively limited.