In September 1996, the United States was the first country to sign the Comprehensive Nuclear-Test-Ban Treaty (CTBT), an international agreement to ban all nuclear test explosions, now signed by 177 nations. The treaty is intended to impede the development of nuclear weapons as part of the international nonproliferation regime. The treaty is not yet in effect because it has not been ratified by enough countries—including the United States. As a result, many of its verification provisions have not yet been fully implemented. When implemented, the American Geophysical Union (AGU) and the Seismological Society of America (SSA) are confident that the combined worldwide monitoring resources will meet the verification goals of the CTBT.