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U.S. Department of State

Diplomacy in Action

CTBTO Preparatory Commission

Fact Sheet
Bureau of Arms Control, Verification, and Compliance
March 29, 2011


[This fact sheet has been updated; see current version.]

Key Point: The Preparatory Commission (PrepCom) for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) was created to carry out the necessary preparations for the effective implementation of the Comprehensive Nuclear-Test-Ban Treaty once it enters into force. The PrepCom establishes and manages the development of the institutions for international data collection, analysis and dissemination that will contribute to Treaty verification. It also works to encourage additional states to sign and ratify the Treaty.

The PrepCom is based in Vienna, Austria, and is composed of all States that have signed the Treaty. It is responsible for ensuring the development of the verification regime, so that it is operational when the treaty enters into force. The PrepCom is also responsible for preparing for the first session of the Conference of the States Parties, at the conclusion of which the PrepCom will cease to exist. In addition to its member States, the PrepCom has established a Provisional Technical Secretariat, staffed by more than 260 people from over 70 states, which has the following duties:

  1. Manage the overall installation and provisional operations and maintenance of the International Monitoring System (IMS).
  2. Operate the International Data Centre, which receives data from IMS stations, analyzes and produces monitoring reports, and disseminates the IMS data and its IDC products to State Signatories.
  3. Prepare for the conduct of the on-site inspection element of the verification regime.
  4. Provide other support to the members of the PrepCom.

For more information about the CTBTO Preparatory Commission, click here.


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