The
Outer Space Treaty, formally the
Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, is a
treaty that forms the basis of international
space law. The treaty was opened for signature in the United States, the United Kingdom, and the
Soviet Union on 27 January 1967, and entered into force on 10 October 1967. As of September 2015, 104 countries are parties to the treaty, while another 24 have signed the treaty but have not completed ratification. In addition, the
Republic of China (Taiwan), which is currently only recognized by , 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.