User:Jakew/UNT

International treaties
Signed in Moscow on August 5, 1963 by representatives of the United States, the Soviet Union, and the United Kingdom, the Limited Test Ban Treaty agreed to ban nuclear testing in the atmosphere, in space, and underwater. Due to the Soviet government's concern about the need for the on-site inspections, underground tests were excluded from the ban. 108 countries would eventually sign the treaty, with the significant exceptions of France and China.

In 1974, the United States and the Soviet Union signed the Threshold Test Ban Treaty, which banned underground tests with yields greater than 150 kilotons. By the 1990s, technologies to monitor and detect underground tests had matured to the point that tests of one kiloton or over could be detected with high probability, and in 1996 negotiations began under the auspices of the United Nations to develop a comprehensive test ban. The resulting Comprehensive Test Ban Treaty was signed in 1996 by the United States, Russia, United Kingdom, France, and China.

Monitoring
In the late 1940s, the United States began to develop the capability to detect atmospheric testing using air sampling; this system was able to detect the first Soviet test in 1949. Over the next decade, this system was improved, and network of seismic monitoring stations was established to detect underground tests. Development of the Threshold Test Ban Treaty in the mid-1970s led to an improved understanding of the relationship between test yield and resulting seismic magnitude.

When negotiations began in the mid-1990s to develop a comprehensive test ban, the international community was reluctant to rely upon the detection capabilities of individual nuclear weapons states (especially the United States), and instead wanted an international detection system. The resulting International Monitoring System consists of a network of a total of 321 monitoring stations and 16 radionuclide laboratories. Fifty "primary" seismic stations send data continuously to the International Data Center, along with 120 "auxiliary" stations which send data on request. The resulting data is used to locate the epicentre, and distinguish between the seismic signatures of an underground nuclear explosion and an earthquake. Additionally, eighty radionuclide stations detect radioactive particles vented by underground explosions. Certain radionuclides constitute clear evidence of nuclear tests; the presence of noble gases can indicate whether an underground explosion has taken place. Finally, eleven hydroacoustic stations and sixty infrasound stations monitor underwater and atmospheric tests.