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United Nations Agencies

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Preparatory Commission for the Comprehensive Nuclear Test-Ban Treaty Organization


The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) was set up in 1996 with its headquarters in Vienna, Austria. It is an interim organization tasked with building up the verification regime of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in preparation for the Treaty's entry into force, as well as promoting the Treaty's universality. 

Its provisional secretariat has nearly has nearly 300 multi-disciplinary professional and support staff from around 90 Member States.  

The CTBTO is financed mainly through assessed contributions by Member States. Its budget in 2022 is US$125 920 000. 

   The Commission consists of two main organs:  

  • A plenary body composed of all States Signatories (Member States), which is also referred to as the Preparatory Commission. This is assisted by three groups:  a working group on administrative and financial issues (Working Group A), another on verification-related issues (Working Group B) and an advisory group. 
  • The Provisional Technical Secretariat (PTS), which assists the plenary body in carrying out its activities. The PTS has three technical divisions: the International Monitoring System (IMS) Division, the International Data Centre (IDC) Division and the On-Site Inspection (OSI) Division. These are supported by a Legal and External Relations Division, a Division of Administration and Knowledge Management and Human Resources Services.