The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is an international organization that will be established upon the entry into force of the Comprehensive Nuclear-Test-Ban Treaty, a Convention that outlaws nuclear test explosions. Its seat will be Vienna, Austria. The organization will be tasked with verifying the ban on nuclear tests and will operate therefore a worldwide monitoring system and may conduct on site inspections. The Preparatory Commission for the CTBTO, and its Provisional Technical Secretariat, were established in 1997 and are headquartered in Vienna, Austria.
The Comprehensive Nuclear-Test-Ban Treaty will enter into force 180 days after the Treaty has been ratified by 44 States, listed in Annex 2 of the Treaty, which were designated to have a nuclear reactor or at least some advanced level of nuclear technology. As of March 2015, 41 of these Annex 2 states have signed the treaty and 36 have ratified. India, North Korea and Pakistan have not signed or ratified the treaty; China, Egypt, Iran, Israel and the United States have signed but have not ratified.
The Preparatory Commission was established in 1997 and is tasked with making preparations for effective implementation of the Treaty, in particular by establishing its verification regime. The main task is establishing and provisionally operating the 337-facility International Monitoring System (IMS), including its International Data Centre (IDC) and Global Communications Infrastructure (GCI). The Commission is tasked also with the development of operational manuals, including a manual to guide conduct of on-site inspections.