Following the world's first nuclear test by the US in 1945, the former Soviet Union, United Kingdom, France, and China also succeeded in developing nuclear weapons and repeatedly conducted nuclear tests. These tests injured and killed many persons and caused massive global contamination. As a result, the Partial Test Ban Treaty in 1963 banned atmospheric testing but allowed it to continue underground.
With the end of the Cold War, underground nuclear tests were suspended by the Soviet Union in 1990, United Kingdom and the US in 1992, and France and China in 1996. On September 10, 1996, the Comprehensive Test Ban Treaty (CTBT) was adopted by the UN General Assembly. However, because the treaty does not cover computer-simulated tests and tests not accompanied by explosions (sub-critical tests), the US defied the international call for a world without nuclear weapons and conducted sub-critical tests in 1997. It was learned later that Russia carried out similar tests.
India conducted underground nuclear tests in May 1998. Following India’s example, Pakistan, with a long-standing territorial dispute with India, carried out its own tests. The Democratic People’s Republic of Korea (DPRK) conducted underground nuclear tests twice–on October 2006 and May 2009.
Of the forty-four states whose ratification is necessary for entry into force of the CTBT, nine, including the United States, China, and Israel, have not ratified the Treaty. Among the nine, India, North Korea and Pakistan have not even signed it, claiming that the Nuclear Non-proliferation Treaty (NPT) and CTBT are unfair treaties contributing to the monopoly of nuclear weapons by five official nuclear states. Today, the nuclear non-proliferation system is in danger of total collapse.
Worldwide, it is estimated that 2,115 nuclear tests had been conducted as of October 2014.