The PTBT banned nuclear weapons testing in the atmosphere, outer space, and underwater, reducing radioactive fallout and establishing a norm against non-underground tests.
Key Facts
- Signed
- 5 August 1963
- Entered into force
- 10 October 1963
- Original signatories
- Soviet Union, United Kingdom, United States
- Total states party
- 126
- States signed but not ratified
- 10
- Last atmospheric test by non-signatory
- China, 1980
By the Numbers
Location
Cause → Event → Consequence
Public anxiety over growing nuclear fallout from thermonuclear weapon tests, combined with fears about nuclear proliferation and the escalating arms race, drove governments to seek a test ban. Negotiations for a comprehensive ban stalled over disagreements about verifying underground tests and Soviet objections to intrusive inspection methods.
The governments of the Soviet Union, the United Kingdom, and the United States signed the Partial Test Ban Treaty in Moscow on 5 August 1963. The treaty prohibited nuclear weapons test detonations in the atmosphere, outer space, and underwater, permitting only underground tests, and was opened for signature by other nations upon conclusion.
The treaty entered into force on 10 October 1963 and attracted 123 additional state parties over time. Atmospheric radioactive particle concentrations declined substantially following its enactment. While it did not stop proliferation or the arms race, it established a lasting taboo against non-underground testing; since 1980, all declared nuclear states have confined tests to underground settings.
Political Outcome
Nuclear testing in the atmosphere, outer space, and underwater was banned; all declared nuclear states have conducted only underground tests since 1980.
Unrestricted atmospheric and underwater nuclear testing by major powers, with rising global fallout levels.
Atmospheric, outer space, and underwater tests prohibited; non-underground testing became internationally stigmatized.