The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is an international organization headquartered at the Vienna International Centre. Because the Comprehensive Nuclear-Test-Ban Treaty (CTBT) has not yet entered into force, the body that exists today is formally the Preparatory Commission for the CTBTO, established by a Resolution of the Meeting of States Signatories in New York on 19 November 1996, shortly after the treaty opened for signature on 24 September 1996.
The Preparatory Commission has two principal organs: a plenary body of States Signatories and the Provisional Technical Secretariat (PTS), which carries out day-to-day work. Its central mandate is to build and provisionally operate the treaty's verification regime, which has four components:
- The International Monitoring System (IMS), a global network of seismic, hydroacoustic, infrasound and radionuclide stations designed to detect nuclear explosions.
- The International Data Centre (IDC) in Vienna, which processes and distributes IMS data to States Signatories.
- On-Site Inspections (OSI), available only once the treaty enters into force, to investigate suspected nuclear tests.
- Consultation and clarification procedures among States Signatories.
The CTBTO's monitoring data has detected each of the announced nuclear tests by the Democratic People's Republic of Korea (2006, 2009, 2013, 2016 twice, and 2017) and has also been used for civilian purposes, including tsunami warning and tracking radionuclide dispersion after the 2011 Fukushima Daiichi accident.
Entry into force of the CTBT requires ratification by the 44 states listed in Annex 2 of the treaty. As of writing, several Annex 2 states — including the United States, China, Egypt, Iran, and Israel — have signed but not ratified, while the DPRK, India, and Pakistan have neither signed nor ratified. Until that threshold is met, the CTBTO remains in its preparatory phase. The Executive Secretary heads the PTS; Robert Floyd of Australia took office on 1 August 2021.
Example
In September 2017, the CTBTO's International Monitoring System detected seismic signals from the Democratic People's Republic of Korea's sixth declared nuclear test and shared the data with States Signatories within hours.
Frequently asked questions
No. It is an autonomous international organization with a cooperation agreement with the UN, similar in status to the IAEA and OPCW, and reports annually to the UN General Assembly.
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