High Quality Content by WIKIPEDIA articles! The parties to the Comprehensive Nuclear-Test-Ban Treaty (CTBT) are the states that have signed and ratified the international agreement banning all nuclear explosions in all environments. If the treaty enters into force, these states will also be member states of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). States not party to the treaty are also listed, including those that are signatories and those are not. States Signatories are Members of the CTBTO Preparatory Commission.