U.S. President Barack Obama set out his vision for a world free of nuclear weapons on Sunday, vowing to involve all states with atomic weapons in the process of reducing arsenals.
Obama also said North Korea had broken the rules with a rocket launch earlier on Sunday and called on Pyongyang to abandon its efforts to acquire nuclear weapons.
Russia and the United States said on Saturday they would start talks on a new deal to cut nuclear warheads before the end of the month. On Wednesday, Russian President Dmitry Medvedev and Obama agreed to pursue a new arms deal, in accordance with U.S. and Russian obligations in the nuclear Non-Proliferation Treaty (NPT).
Here are some key facts about the treaty, regarded as the cornerstone of global efforts to prevent the proliferation of nuclear weapons:
* PURPOSE OF THE NPT:
-- The objective of the treaty, which took effect in 1970, is to halt the spread of nuclear weapons-making capability, guarantee the right of all members to develop nuclear energy for peaceful ends and -- for the original five nuclear weapons powers -- to phase out their arsenals.
-- The treaty defines nuclear-armed states as those that "manufactured and exploded a nuclear weapon or other nuclear device prior to January 1, 1967." They are the United States, Britain, France, China and Russia (which assumed rights and obligations from the Soviet Union). The five are the permanent members of the U.N. Security Council.
-- A total of 189 countries are party to the NPT. North Korea dropped out in 2003. Nuclear states are bound not to transfer nuclear weapons or to help non-nuclear states obtain them.
-- South Africa signed the treaty in 1991 and admitted producing nuclear devices until 1970.
-- Two non-signatories, India and Pakistan, developed nuclear arsenals and the other, Israel, is widely assumed to have one but has never confirmed it publicly.
-- North Korea signed in 1985 but left after U.S. officials confronted it with evidence they said pointed to a covert enrichment program. Pyongyang also expelled inspectors from the International Atomic Energy Agency (IAEA).
-- U.S. President Barack Obama said on Sunday North Korea, which tested a nuclear device in 2006, had violated U.N. resolutions with what analysts believe was effectively a test of a ballistic missile designed to carry a warhead potentially as far as Alaska.
* TREATY TRADEOFF:
-- Non-nuclear signatories must not develop or acquire such weapons but are given an assurance of assistance in developing nuclear energy for peaceful purposes, monitored by inspectors from the Vienna-based IAEA.
* ESCAPE CLAUSE:
-- The treaty is divided into 11 articles, including one that enables a state to withdraw "if it decides that extraordinary events ... have jeopardized the supreme interests of its country." A state must give three months' notice to other treaty parties and the U.N. Security Council.
* INDEFINITE EXTENSION:
-- At the 1995 NPT review conference, the treaty was extended indefinitely at the behest of nuclear weapons powers. Developing countries agreed to the extension after a commitment from weapons states to step up disarmament, ease access to nuclear energy for development and seek a nuclear weapons-free zone in the Middle East. They say these pledges have not been fully honored.
(Writing by David Cutler, London Editorial Reference Unit)