List of parties to the Partial Nuclear Test Ban Treaty

The list of parties to the Partial Test Ban Treaty encompasses the states who have signed and ratified or acceded to the international agreement prohibiting all test detonations of nuclear weapons except underground.

On August 5, 1963, the Partial Test Ban Treaty (PTBT) was opened for signature. The principal state authors (the Soviet Union, the United Kingdom, and the United States) signed the treaty that day. The PTBT came into force and closed for signature on October 10, 1963 with the ratification by the three principal states. Since then, states that did not sign the treaty can now only accede or succeed to it.

As of October 2018, 125 UN member states have ratified or acceded to the treaty, most recently Montenegro on 3 June 2006.^[1] In addition, the Republic of China (Taiwan), which is currently only recognized by 11 UN member states, ratified the treaty prior to the United Nations General Assembly's vote to transfer China's seat to the People's Republic of China (PRC) in 1971.^[2] A further 10 states have signed but not ratified the treaty. The instrument of ratification, accession, or succession is deposited at the respective capitals of the principal states of the treaty: Moscow, London, and Washington, D.C.