How was nuclear testing progressively stopped, starting in the 1990s?
The Soviet Union declared a moratorium on nuclear testing in 1991, which was followed by U.S. legislation that imposed a moratorium until 1993 and subsequently through 1994, provided no other country tested. The United States announced its commitment to concluding a comprehensive test ban treaty early in 1993. Prospects for negotiating such a treaty increased significantly during this time since the Russian Federation, the United States and the United Kingdom all had a moratorium on nuclear testing in place. This set the stage for the successful CTBT negotiations that took place from 1994 through 1996.