Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization
![](/Images/godic/202501/20/CTBT_Participation.svg1959.png")
![Lassina Zerbo, Executive Secretary of the Provisional Secretariat](/Images/godic/202501/20/CTBTO_Executive_Secretary_Lassina_Zerbo1959.jpg")
![Infrasound arrays at IMS infrasound station IS18, Qaanaaq, Greenland.](/Images/godic/202501/20/Infrasound_Arrays1959.jpg")
![IMS Radionuclide station RN20, Beijing, China. The station is also equipped for noble gas monitoring.](/Images/godic/202501/20/CTBT_Radionuclide_Station_RN202000.jpg")
The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization, CTBTO Preparatory Commission or CTBTO Prep Com is an international organization based in Vienna, Austria, that is tasked with preparing the activities of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The organization was established by the states that signed the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in 1996. Its main purpose is twofold: to promote the entry into force of the CTBT, which bans all nuclear explosions, and to establish a global verification regime to ensure that all nuclear tests are detected.