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PARIS: North Korea's announcement Monday that it has carried out its threat to explode a nuclear device marks the first real life test of the world's deadliest weapon to take place anywhere in the world since 1998.
Nuclear weapons testing has in principle been banned since 1996; only India and Pakistan are known to have detonated devices since then.
Key events in the history of nuclear weapons:
1945: The United States develops the first functioning atomic bomb, which it explodes in the desert of New Mexico. It drops two of the devices on the Japanese cities of Hiroshima and Nagasaki, the only occasions on which nuclear bombs have been used in anger to date.
1946-63: The US, rapidly joined by the Soviet Union and then Britain and France, carry out a large number of weapons tests, many of them above ground.
Test sites include deserts in the western United States, French Algeria and Australia, and Pacific atolls. The extreme danger to life posed by nuclear fall-out only gradually becomes widely known.
1963: The main powers sign a Limited Test Ban Treaty, banning explosions in the atmosphere, in space or under water. Most subsequent tests take place deep underground. China begins testing nuclear weapons in 1964.
1968: The Nuclear Non-Proliferation Treaty, signed over the years by 188 countries, aims both to persuade existing nuclear powers to get rid of their weapons and to prevent other countries obtaining them. Israel, which is widely reported to have such arms, refuses to sign, as do India and Pakistan, which have made no secret of possessing them. North Korea withdraws from the NNPT in 2003.
1972-93: The United States and the Soviet Union — Russia after 1991 — sign a series of treaties aimed at cutting their huge nuclear arsenals and reducing the number of tests.
1995: Jacques Chirac, the newly-elected president of France, says he will break a three-year moratorium on all tests by holding a new series of underground blasts in the Pacific.
1996: Drafting of a Comprehensive Test Ban Treaty, intended to prevent all test nuclear blasts of any kind. Although signed by 172 nations it has still not been ratified by several key states, including the US and China.
1998: India, followed in short order by its longtime foe Pakistan, carries out a series of underground tests.
2006: North Korea says it has carried out its first nuclear weapons test, calling it a “historic event”.
In all, just over 2,048 nuclear weapons tests are officially reported to have taken place throughout the world since the first blasts in 1945. Of that total, 1,032 were carried out by the United States, and 715 by the Soviet Union.
