International Monitoring System

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization, or CTBTO Preparatory Commission, is an international organization based in Vienna, Austria, that is tasked with building up the verification regime of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The organization was established by the States Signatories to the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in 1996.