The nuclear Nonproliferation Treaty (NPT) which entered into force in March 1970, seeks to inhibit the spread of nuclear weapons. Its 190 states-parties are classified in two categories: nuclear-weapon states (NWS) consisting of the United States, Russia, China, France, and the United Kingdom—and non-nuclear-weapon states (NNWS). Under the treaty, the five NWS commit to pursue general and complete disarmament, while the NNWS agree to forgo developing or acquiring nuclear weapons. These are the first two “pillars” of the treaty. The third pillar ensures that non-nuclear weapon states can access and develop nuclear technology for
With its near-universal membership, the NPT has the widest adherence of any arms control agreement, with only South Sudan, India, Israel, and Pakistan remaining outside the treaty. The treaty, which was indefinitely extended in 1995, calls for a review conference every five years to assess progress on achieving the treaties key objectives and provide opportunities to discuss new measures to strengthen the treaty.
The 2015 Review Conference will cover many issues including the status of disarmament, the proliferation of nuclear weapons technology, developments in the peaceful use of nuclear energy and strengthening provisions to prevent withdrawal from the treaty.
The following timeline provides a brief history of events related to the nuclear Nonproliferation Treaty from the 1950s to the present.
Skip to: 1950s, 1960s, 1970s, 1980s, 1990s, 2000s, 2010s
July 29, 1957: The International Atomic Energy Agency (IAEA) comes into existence with the mission of promoting and overseeing the peaceful use of nuclear technology. President Dwight Eisenhower had called for the creation of such an agency in his December 1953 “Atoms for Peace” proposal.
October 17, 1958: Ireland proposes the first resolution at the United Nations to prohibit the “further dissemination of nuclear weapons.” Back to Top
February 13, 1960: France conducts its first nuclear test explosion, becoming the world’s fourth nuclear-armed state, after the United States, the Soviet Union, and the United Kingdom.
December 4, 1961: The UN General Assembly unanimously approves Resolution 1665, which is based on the earlier Irish draft resolution and calls for negotiations to prevent the spread of nuclear weapons to additional states. The resolution says that countries already having nuclear weapons would “undertake to refrain from relinquishing control” of them to others and would refrain “from transmitting information for their manufacture to States not possessing” them. Countries without nuclear weapons would agree not to receive or manufacture them. These ideas formed the basis of the NPT.
March 21, 1963: In a press conference, President John Kennedy warns, “I see the possibility in the 1970s of the president of the United States having to face a world in which 15 or 20 or 25 nations may have [nuclear] weapons. I regard that as the greatest possible danger and hazard.” Kennedy made this statement a month after a secret Department of Defense memorandum assessed that eight countries—Canada, China, India, Israel, Italy, Japan, Sweden, and West Germany—would likely have the ability to produce nuclear weapons within 10 years. The study also calculated that, beyond 10 years, the future costs of nuclear weapons programs would diminish and that several more states would likely be able to pursue nuclear weapons, especially if unrestricted testing continued. The risks of such proliferation, which the existing nuclear powers sought to curtail or prevent, largely served as an impetus for drafting the NPT. Today the IAEA assesses that nearly 30 states are capable of developing nuclear weapons, but only nine states are known to possess them.
October 16, 1964: China conducts its first nuclear test explosion, becoming the world’s fifth nuclear-armed state and leading to the acceleration of India’s nuclear program.
August 17, 1965: The United States submits to the Eighteen Nation Disarmament Committee its first draft proposal to prevent the spread of nuclear weapons. The Soviet Union submits its first draft a month later.
February 14, 1967: The Treaty of Tlatelolco, establishing Latin America and the Caribbean as a nuclear-weapon-free zone, is opened for signature. It is the first of five such regional zones to be negotiated. The other zones cover Africa, Southeast Asia, the South Pacific, and Central Asia.
August 24, 1967: The United States and Soviet Union separately introduce identical draft treaties to the Eighteen Nation Disarmament Committee on preventing the spread of nuclear weapons. Circa 1967: Israel secretly acquires the capability to build a nuclear explosive device.
June 12, 1968: The UN General Assembly adopts Resolution 2373, endorsing the draft text of the nuclear Nonproliferation Treaty (NPT). The vote was 95 to 4 with 21 abstentions. The four no votes were Albania, Cuba, Tanzania, and Zambia.
July 1, 1968: The NPT is opened for signature and is signed by the Soviet Union, the United Kingdom, and the United States. Article IX of the treaty established that entry into force would require the treaty’s ratification by those three countries (the treaty’s depositories) and 40 additional states. China and France, the other two recognized nuclear-weapon states under the treaty, do not sign it. China argued the treaty was discriminatory and refused to sign or adhere to it. France, on the other hand, indicated that it would not sign the treaty but “would behave in the future in this field exactly as the States adhering to the Treaty.” Both states acceded to the treaty in 1992. Back to Top
March 5, 1970: The NPT enters into force with 46 states-parties.
May 18, 1974: India is the first non-nuclear-weapon state, as defined by the NPT, to conduct a nuclear test. India was not an NPT member, and New Delhi insisted the test was a “peaceful” nuclear explosion to mollify international criticism. In 1997, however, Raja Ramanna, the former director of India’s nuclear program, admitted that the 1974 blast was a weapons test, stating, “I just want to make clear that the test was not all that peaceful.” Despite India’s original characterization of the test as peaceful, it raised alarms within the international community, particularly in Canada and the United States. Both countries had supplied facilities and materials to India for peaceful nuclear purposes and felt betrayed by India’s use of them to conduct a nuclear explosion. The United States reacted by leading other nuclear exporters to form the voluntary Nuclear Suppliers Group in 1975 to coordinate stricter restrictions on global nuclear trade. Originally, the NPT allowed non-nuclear-weapon states to conduct peaceful nuclear explosions. During the 2000 NPT review conference, however, treaty states-parties agreed to ban such tests in light of the Comprehensive Test Ban Treaty, which was completed in 1996.
September 3, 1974: The IAEA publishes the “trigger list” developed by the Zangger Committee, identifying nuclear items that require IAEA safeguards as a condition of export.
May 30, 1975: The 91 states-parties to the NPT hold the treaty’s first review conference. The treaty members decide to hold such conferences to review the implementation of the treaty every five years.
January 11, 1978: States participating in the voluntary Nuclear Suppliers Group provide the IAEA with a common set of guidelines they will follow in making nuclear exports. The IAEA publishes the guidelines the next month. Back to Top
The decade was dominated by the Cold War superpower competition of the United States and the Soviet Union. Much of the world held its collective breath during the first years of the decade as tensions and the nuclear arms race heated up between the two rivals, leading to popular anti-nuclear protests worldwide and the nuclear freeze movement in the United States. The international community exhaled a bit in the second half of the decade as the United States and the Soviet Union earnestly sat down at the arms negotiating table and for the first time eliminated an entire category of nuclear weapons through the 1987 Intermediate-Range Nuclear Forces Treaty. The two countries also proceeded to negotiate cuts to their strategic nuclear forces, which ultimately would be realized in the landmark 1991 Strategic Arms Reduction Treaty. Although the U.S.-Soviet nuclear arms race was center stage, efforts to advance and constrain the nuclear weapons ambitions and programs of other countries played out in the wings, sometimes as part of the superpower drama. For instance, the United States shunted nonproliferation concerns aside in ignoring Pakistan’s nuclear weapons program because of that country’s role in fighting Soviet forces inside Afghanistan. Meanwhile, Iraq, North Korea, and South Africa advanced their nuclear weapons efforts in relative secrecy. In this decade, Iran began to secretly acquire uranium-enrichment-related technology from Pakistani suppliers. Taiwan’s covert nuclear weapons program, however, was squelched by U.S. pressure. Other nonproliferation gains included a joint declaration by Argentina and Brazil to pursue nuclear technology only for peaceful purposes, alleviating fears of a nuclear arms race between the two, and the conclusion of a nuclear-weapon-free zone in the South Pacific. Moreover, the NPT added 30 new states-parties during the decade, including North Korea. Back to Top
April 3, 1991: The UN Security Council adopts Resolution 687 requiring Iraq to eliminate its secret nuclear weapons program, which was revealed after the Iraqi defeat in the 1991 Persian Gulf War. Iraq had illegally pursued the weapons program despite being an NPT state-party. Following the adoption of Resolution 687, the IAEA gained a greater understanding of Iraq’s clandestine program and dismantled and sealed its remnants. The realization that Iraq pursued such a program undetected in spite of agency inspections served as a key impetus to strengthen IAEA safeguards. That effort eventually produced the Model Additional Protocol. The IAEA maintained a presence in Iraq until its inspectors were forced to withdraw in late 1998 on the eve of U.S. and British military strikes against Iraq. Throughout the 1990s, the United States expressed concern that Iraq maintained the ability and intention to reconstitute its nuclear weapons program, as well as other efforts to produce other “weapons of mass destruction” (WMD). These suspicions led to the adoption of Security Council Resolution 1441 in November 2002, declaring Iraq in material breach of its obligations to comply with international inspections and establishing a renewed inspection process. Although those inspections did not uncover evidence that Iraq had reconstituted its nuclear weapons program, the United States and the United Kingdom asserted that Iraq continued to pursue unconventional arms and, on March 20, 2003, led a military invasion to topple Iraq’s leadership. Inspections afterward revealed that the U.S. and British allegations were wrong.
July 10, 1991: South Africa accedes to the NPT. Two years later, the South African government admits that it had covertly built six completed nuclear devices and then dismantled them before joining the accord. The move to get rid of the weapons was seen as preparation for the coming end of apartheid rule.
March 9, 1992: China accedes to the NPT.
May 23, 1992: Belarus, Kazakhstan, and Ukraine sign the Lisbon Protocol committing to join the NPT as non-nuclear-weapon states. All three had nuclear weapons when they were Soviet republics. On December 5, 1994, Ukraine becomes the last of the three to accede to the NPT.
August 3, 1992: France, the last of the five recognized nuclear-weapon states, accedes to the NPT.
March 12, 1993: North Korea announces its intention to withdraw from the NPT, but it suspends that withdrawal on June 11, 1993.
April 1, 1993: The IAEA declares North Korea in noncompliance with its safeguards obligations and refers Pyongyang to the UN Security Council.
April 11, 1995: The UN Security Council adopts Resolution 984 acknowledging the unilateral pledges by the five nuclear-weapon states not to use or threaten to use nuclear weapons against non-nuclear-weapon states-parties to the NPT. The move is seen as a way to win greater support for the possible indefinite extension of the treaty.
May 11, 1995: NPT states-parties agree to the treaty’s indefinite extension. Article X of the NPT called for a conference of states-parties to be held 25 years after the treaty’s entry into force in order to determine whether the treaty would remain in force indefinitely or for other additional periods of time. This conference was held in 1995 and began with considerable uncertainty regarding the nature of any extension. Non-nuclear-weapon states, particularly developing countries belonging to the Nonaligned Movement, expressed disappointment with the lack of progress toward nuclear disarmament and feared that a decision to extend the treaty indefinitely would by default enable the nuclear-armed states to hold on to their nuclear arsenals in perpetuity and avoid any accountability in eliminating them. At the conference, Indonesia and South Africa proposed tying the treaty’s indefinite extension to a decision to strengthen the treaty review process. They also linked it to establishment of a set of principles and objectives on nuclear nonproliferation and disarmament to hold NPT states-parties, particularly the nuclear-weapon states, accountable to their commitments. These principles and objectives include completion of the Comprehensive Test Ban Treaty and negotiations on the cutoff of fissile material production for weapons purposes. The conference also adopted a resolution calling for establishment of a zone free of weapons of mass destruction in the Middle East. This resolution was intended to win support for the indefinite NPT extension from Arab states, which objected to Israel’s status outside the NPT and its assumed possession of nuclear weapons. Although only a majority of states-parties was required to approve the indefinite extension, the agreed package of decisions obtained enough support that such a vote was not required.
September 24, 1996: The Comprehensive Test Ban Treaty outlawing nuclear explosions is opened for signature. The treaty has yet to enter into force because not all of the requisite states, including China, India, Pakistan, and the United States, have ratified it.
May 15, 1997: The IAEA adopts the Model Additional Protocol, a voluntary safeguards agreement for a state to give the agency greater powers to verify that illegal nuclear weapons-related activities are not taking place inside that state. The protocol was developed in response to Iraq’s and North Korea’s illicit actions under the treaty.
May 11 & 13, 1998: India conducts nuclear tests for the second time.
May 28, 1998: In response to India, Pakistan, a nonsignatory to the NPT but a non-nuclear-weapon state by the treaty’s terms, conducts its first set of nuclear test explosions. Back to Top
May 22, 2000: The NPT states-parties agree to a 2000 review conference final document that outlines the so-called 13 Steps for progress toward nuclear disarmament, including an “unequivocal undertaking by the nuclear-weapon States to accomplish the total elimination of their nuclear arsenals.”
January 10, 2003: North Korea announces its withdrawal from the NPT. North Korea initially announced its intent to withdraw from the NPT a decade earlier following suspicions of NPT violations. After holding talks with the United States, North Korea suspended that withdrawal in June 1993, just a day before it would have come into effect. It further agreed to give up its nuclear weapons program under a 1994 agreement with the United States. Following the collapse of that agreement in 2002, North Korea declared January 10, 2003, that, with only one day remaining of its previous three-month notification requirement to withdraw from the NPT, its withdrawal would come into effect a day later. Although the legality of North Korea’s process of withdrawal remains in question, subsequent calls by the UN and the IAEA for Pyongyang to return to the NPT demonstrate a recognition that it is currently outside the treaty. Article X of the NPT recognizes the right of states to withdraw from the treaty if that party’s “supreme interests” are jeopardized by “extraordinary events.” States are required to give notice three months in advance before such a withdrawal would take effect. In light of North Korea’s withdrawal and subsequent development of nuclear weapons, the 2005 NPT review conference considered ways to ensure that states that withdraw from the treaty are not able to use technologies and materials obtained while an NPT state-party to pursue nuclear weapons. Discussions of these various proposals are still ongoing.
June 6, 2003: The IAEA issues a report detailing Iranian clandestine nuclear activities that Tehran failed to report to the agency, in violation of its safeguards agreement.
December 19, 2003: Libya announces that it will dismantle its WMD programs, including a secret nuclear weapons program, and agrees to IAEA inspections and adherence to an additional protocol.
September 19, 2005: North Korea commits to abandoning its nuclear weapons and programs and returning to the NPT and to IAEA safeguards in an agreement of the six-party talks on North Korean denuclearization.
September 24, 2005: The IAEA finds Iran in noncompliance with its safeguards obligations after nearly two years of inspections into its undeclared nuclear activities. The agency in February 2006 refers Iran to the UN Security Council, which adopts three sanctions resolutions against Iran over the next two years. IAEA investigations continue into Iran’s past and current nuclear activities.
October 9, 2006: North Korea conducts its first nuclear test explosion.
February 13, 2007: The six-party talks on North Korea’s denuclearization yields an “initial actions” plan to implement Pyongyang’s September 2005 pledge to abandon its nuclear weapons and programs. These initial actions include the shutdown and disablement of North Korea’s Yongbyon nuclear reactor complex and a declaration of its nuclear programs.
September 6, 2008: The Nuclear Suppliers Group agrees to permit trade in nuclear material and technology with India, despite that country’s status as a nonparty to the NPT and de facto nuclear-weapon state.
April 14, 2009: North Korea ends its participation in the six-party talks, after its launch of a long-range rocket draws sanctions from the UN Security Council. North Korea declares it will reverse its 2007 commitments, and resume its nuclear programs.
May 25, 2009: North Korea conducts a second announced nuclear test.
September 24, 2009: The UN Security Council, meeting in a special summit-level session, unanimously approves Resolution 1887 on nuclear issues. Back to Top
April 2010: The United States hosts the first Nuclear Security Summit in Washington. At the summit, the 47 participating states commit to securing nuclear material worldwide and combatting the threat of nuclear terrorism and many states make specific commitments to bolster nuclear security.
November 2010: President Barack Obama announces US support for India’s participation in the Nuclear Suppliers Group, the Wassenaar Arrangement, the Australia Group and the Missile Technology Control Regime. In December of 2010, French President Sarkozy also expresses backing for India’s inclusion in the Nuclear Suppliers Group.
February 5, 2011: The New START treaty enters into force. The US and Russia agree to reduce strategic and offensive arms. The treaty’s central limits must be reached by February 5, 2018. New START reduces the number of deployed nuclear warheads that each state can have to 1,550 each.
June 2011: The United Kingdom announces voluntary planned reductions in its deployed nuclear forces set to be accomplished by early 2015. When complete, the United Kingdom will have 120 deployed strategic warheads, with 60 warheads in reserve to support the maintenance and management of the operational force. All excess warheads will be dismantled by the mid-2020s.
March 2012: The second Nuclear Security Summit is held in Seoul, South Korea. The summit built on the commitments of the previous 2010 summit and adds new goals, such as protecting radioactive sources and increasing the synergy between nuclear security and safety.
November 2012: The conveners (Russia, the United Kingdom, the United States and the UN) of a conference to establish a weapons of mass destruction free zone in the Middle East announce that the conference will be postponed because not all states in the region agree on an agenda for the conference.
December 2012: North Korea successfully launches a satellite into space with a Unha-3 space launch vehicle. Pyongyang is prohibited from space launches by UN Security Council resolutions because some of the technology is directly applicable to ballistic missile development. Despite this success, experts assess that North Korea remains years away from development of an ICBM, given the many technical differences between the two types of systems.3
February 12, 2013: North Korea conducts their third nuclear test. The test was done at the Punggye-ri Test Site in an underground bunker. In a KCNA statement, issued shortly after the test, Pyongyang says it will continue testing and building its arsenal until the United States recognized its right to launch satellites and develop its nuclear program.
March 2013: Norway hosts the first Conference on the Humanitarian Impact of Nuclear Weapons, with participation from 127 states. The conference focused on scientific findings on the impact of nuclear weapons use on humans, the environment, and global climate. The five recognized nuclear weapon states (China, France, Russia, the United Kingdom and the United States) all decide not to attend.
November 24, 2013: Iran and the P5+1 reach an interim agreement in Geneva, Switzerland. The agreement creates a temporary hold on several aspects of Iran’s nuclear program in exchange for temporary relief on several Western sanctions. The Interim Agreement represents the first formal agreement between the US and Iran in 34 years. The agreement laid the foundation for the on-going P5+1 talks.
February 2013: A second conference on the Humanitarian Impact of Nuclear Weapons is held in Mexico, with 146 states in attendance. The conference called for greater efforts on disarmament and an initiative to reach new international standards and norms to prohibit the use of nuclear weapons. The nuclear weapon states do not participate in the conference.
March 2014: The third Nuclear Security Summit is held in The Hague, Netherlands to continue the goal of strengthening nuclear security and eliminating civilian stockpiles of weapons-usable material.
May 2014: All five nuclear weapon states sign the protocol for the Central Asian Nuclear Weapons Free Zone (CANFWZ) treaty. The CANFWZ applies to Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan.
November 2014: France ratifies the CANFWZ.
December 2014: A third conference on the Humanitarian Impact of Nuclear Weapons is held in Vienna. The US and the UK decide to attend and China choses to send an observer. Over 150 countries and several international and civil society organizations participate. Over 60 countries sign a pledge to cooperate to “stigmatize, prohibit, and eliminate” nuclear weapons.
January 2015: The United Kingdom ratifies the CANFWZ.
April 2, 2015: A tentative framework agreement is reached by the P5+1 and Iran. The agreement places meaningful limits on Iran’s nuclear program by prohibiting uranium enrichment in Fordow and constraining enrichment at the Natanz facility. A final agreement is set to be reached by June 30, 2015. Back to Top