The Preparatory Commission

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) was established on 19 November 1996 by a Resolution adopted by the Meeting of States Signatories at the United Nations in New York. 

Article II of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) provides for the establishment of an organization to achieve the aims of the Treaty, ensure its implementation and serve as a forum for its members. Since the activities are very extensive and must be fully operational when the Treaty enters into force, the States signing the Treaty decided that it was necessary to establish an interim organization: a Preparatory Commission. This Commission, based in Vienna, Austria, would lay the groundwork required and build up the global verification regime to monitor compliance with the Treaty. 

The first meeting of the Commission was convened by the Secretary-General of the United Nations on 20 November 1996. Following the conclusion of a host country agreement with Austria, the Provisional Technical Secretariat (PTS) was established in Vienna on 17 March 1997, and opened its doors for business on the same day. 

Purpose and activities

According to the Annex of the resolution establishing the Commission, its main purpose is to carry out the necessary preparations for the effective implementation of the CTBT and to prepare for the first session of the Conference of States Parties to the Treaty, which will take place when the CTBT has entered into force.  

The Commission’s duties focus on the promotion of the signing and ratification of the CTBT so that it can enter into force as soon as possible. Entry into force takes place 180 days after the Treaty has been ratified by the 44 States listed in its Annex 2.  These 44 States participated in the negotiations of the Treaty in 1996 and possessed nuclear power or research reactors at the time.  

The other major duty of the Commission is to establish a global verification regime to monitor compliance with the comprehensive ban on nuclear testing, which must be operational when the Treaty enters into force. This huge task involves the build-up of 321 monitoring stations and 16 radionuclide laboratories around the globe, often in extremely remote and challenging locations, to form the International Monitoring System (IMS). It also includes the provisional operation of an International Data Centre (IDC) and the preparation of an on-site inspection capability to be available after entry into force in case of a suspected nuclear test. 

Composition and structure

On signing the CTBT, a State automatically becomes a member of the Preparatory Commission. The Commission consists of two main organs: a plenary body composed of all the States Signatories (also known as the Preparatory Commission) and the Provisional Technical Secretariat (PTS), which assists the Commission in carrying out its activities. 

The Preparatory Commission plenary is assisted by three groups: 

  • Working Group A deals with budgetary and administrative matters, such as the annual budget, financial and staff regulations and rules and legal issues. 

  • Working Group B deals with verification issues. 

  • The Advisory Group advises the Commission and its working groups on financial, budgetary and associated administrative matters. 

Both Working Groups make proposals and recommendations for consideration and adoption by the Preparatory Commission. 

The Advisory Group consists of experts from States Signatories, who are of recognized standing and have experience in financial matters at the international level. 

Standing as an international organization

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is an international organization financed by the CTBT Member States. It has a strong technical focus, with some 80% of its budget allocated to verification-related activities. 

The Resolution establishing the Commission granted it standing as an international organization and gave it the legal authority it needed to function, including the build-up and provisional operation of the verification regime. The Commission also has the authority to negotiate and enter into international agreements. 

The Commission is not part of the United Nations although it follows the UN common system for the international civil service, including practices related to administration, finance and personnel. 

The Commission entered into a relationship agreement with the United Nations in June 2000. This agreement brings the Commission, an independent organization with its own membership and budget, into a formal relationship with the United Nations and provides a framework for cooperation and coordination between the two organizations.  

Such cooperation facilitates the Commission’s task of carrying out the necessary preparations for the effective implementation of the Treaty, including the establishment of the global verification regime. The agreement also allows for the mutual exchange of information and mutual participation in each other’s meetings, and eliminates the need for duplication of common services such as translation and interpretation. 

The UN Secretary-General is the Depositary of the Treaty. This means that the CTBT is open for signature at the headquarters of the United Nations in New York. It also means that States that ratify the Treaty deposit their instruments of ratification with the UN Secretary-General who, in turn, produces the official notifications of the status of the Treaty. 

Under Article XIV of the Treaty, the Secretary-General has the duty to call a Conference of the Treaty’s Ratifying States, on the request of the majority of such States, to consider and decide on what measures may be taken to speed up the ratification process to hasten entry into force. This Conference on Facilitating Entry into Force of the CTBT, commonly known as the Article XIV Conference, has been held every second year since 1999. 

The Preparatory Commission has the authority to enter into IMS facility agreements, which govern the activities of the Commission when establishing, maintaining and upgrading stations in various countries. 

It has concluded Tsunami Warning Agreements with national warning centres in a wide range of Member States, allowing them to receive data from the IMS in near-real time to help issue more timely and precise public alerts.  

It is also a participating organization in the Inter-Agency Committee on Radiological and Nuclear Emergencies (IACRNE) and its Joint Radiation Emergency Management Plan of the International Organizations (the Joint Plan), which facilitates a coordinated and harmonized international response to nuclear and radiological incidents and emergencies.  

Other agreements have been concluded with a number of international organizations, including the Agency for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (OPANAL), the Association of Caribbean States (ACS), the European Centre for Medium-Range Weather Forecast (ECMWF), the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO), the United Nations Development Programme (UNDP) and the World Meteorological Organization (WMO).  


States Signatories provide the Preparatory Commission with the necessary financial support. The Budget of the Preparatory Commission is derived through assessed and voluntary contributions. 

Assessed Contributions

According to the Annex on the Resolution which established the Preparatory Commission, “the costs of the Commission and its activities, including those of the PTS [Provisional Technical Secretariat], shall be met annually by all States Signatories…”  This forms the basis for levying scaled annual dues on Member States, known as assessed contributions. These are based on the Scale of Assessments passed by the UN General Assembly every three years and adjusted to take account of differences between UN membership and the CTBTO’s membership. The adjusted scale is then approved every year by the Preparatory Commission of the CTBTO. 

Non-payment of assessed contributions by a State Signatory after 365 days of receipt of the request for payment affects the voting right of such a Member State until such payment is made. This stricture may only be waived by the Commission if it was judged to be due to circumstances beyond the control of the State Signatory in question. 

View the latest information regarding State Signatories' financial contributions for the latest information regarding State Signatories' financial contributions.

Voluntary contributions

The activities of the Commission may also be funded by voluntary contributions provided by states, international organizations or other entities. Voluntary contributions may be “in-kind” (e.g. equipment) or in cash. They may also include bequests and subventions other than funds held as funds-in-trust by the Executive Secretary. 


Preparatory Commission at a Glance

Chairperson, Preparatory Commission

Vice-Chairperson, Preparatory Commission


Vice-Chairperson, Preparatory Commission


Vice-Chairperson, Preparatory Commission


Vice-Chairperson, Preparatory Commission


Vice-Chairperson, Preparatory Commission


Subsidiary Bodies of the Preparatory Commission

Chairperson, Working Group A

HE Evangelina Lourdes A. BERNAS
The Philippines

Vice-Chairperson, Working Group A


Chairperson, Working Group B


Vice-Chairperson, Working Group B

Netherlands (Kingdom of the)

Vice-Chairperson, Working Group B

South Africa

Advisory Group

Chairperson, Advisory Group

United Kingdom of Great Britain and Northern Ireland

Vice-Chairperson, Advisory Group


United States of America