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Understanding the New Nuclear Weapons Ban

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Understanding the New Nuclear Weapons Ban

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Andrea Berger

Senior Research Associate, The James Martin Center for Nonproliferation Studies

It has been called everything from “the beginning of the end of nuclear weapons”  and a “historic achievement,” to a “shotgun treaty”  and an “ineffective”  and “counterproductive” disarmament measure. 1 On September 20th, a controversial treaty prohibiting nuclear weapons opened for signature. This Treaty on the Prohibition of Nuclear Weapons, or, as some refer to it, Nuclear Weapons Ban Treaty, will enter into force 90 days after the 50th country’s ratification.

The Ban Treaty prohibits the development, testing, use, threat of use, production, manufacture, acquisition, possession, stationing, and stockpiling of nuclear weapons. These prohibitions go substantially beyond existing international treaties on nuclear weapons, such as the Comprehensive Nuclear Test Ban Treaty (CTBT) or the Nuclear Non-Proliferation Treaty (NPT). Whereas the CTBT only prohibits explosive nuclear testing, and the NPT indefinitely grandfathered in nuclear weapons possession by five countries (while committing them to work towards disarmament), the Ban Treaty imposes a universal and absolute prohibition on all members. Any nuclear possessor that signed onto the nuclear weapons ban would be obligated to disarm within a time-bound framework that will be agreed with a “competent international authority” (not yet specified) and the other states parties to the treaty. Furthermore, if one of the states that station U.S. nuclear weapons on its territory as part of NATO’s nuclear umbrella signed on (Belgium, the Netherlands, Germany, Italy, or Turkey), that state would be forced to “ensure the prompt removal of such weapons” and submit a report to the UN Secretary-General on its actions. 2 Reflecting the humanitarian impetus for the treaty, it also includes provisions committing states to offering victim assistance in the event of a nuclear attack or test affecting another state party.

However, the Ban Treaty’s ultimate practical implications are constrained by a stark participatory divide. None of the nuclear weapons possessors, or so-called “umbrella states,” support the treaty, meaning that they are not legally bound by its terms.

The Road to a Ban

The treaty is the brainchild of a group of non-nuclear weapon states and civil society advocates, frustrated by the slow pace of global nuclear disarmament and the continued risk of nuclear conflict. Since 2010, this group has successfully pushed for the reframing of the debate on nuclear weapons to focus on their humanitarian impact and risk of use. The group concluded that in the absence of adequate disarmament progress, it was necessary to delegitimize nuclear deterrence policies and exert normative pressure on the countries who rely upon them. As long as nuclear weapons were not banned outright, these countries reasoned, they could continue to be viewed by the international community as acceptable instruments of security rather than threatening weapons of mass destruction. Other WMD, including biological and chemical weapons, had been banned altogether by the respective conventions decades before. In 2016, six countries drafted, and twenty-eight more co-sponsored, a resolution in the UN General Assembly mandating the commencement of negotiations on a legally binding prohibition.

Nuclear-armed states and their allies opposed the initiative from the outset. They argued that the movement completely ignored the security considerations that led certain countries to rely upon nuclear deterrence in the first place. Progress on disarmament may be slow – as current U.S.-Russia arms reduction efforts illustrate – but when progress is made, they argued, it is both meaningful and durable.

Some nuclear possessors went further, arguing that the initiative was not merely ineffective and unserious, but potentially damaging. The United States circulated a paper among NATO allies, suggesting that a ban treaty could have negative ramifications for alliance activities. 3 Other opponents contended that the ban risked distracting from or undermining key disarmament and nonproliferation treaties, such as the NPT and the CTBT, possibly even threatening their “viability.” 4

Nuclear-armed states and their allies, being in the minority, ultimately lost the numbers game. On October 27, 2016, the UN General Assembly’s First Committee adopted Resolution L.41, “Taking forward multilateral nuclear disarmament negotiations,” with 123 votes in favor, 38 against, and 16 abstentions.

The Negotiating Conference

In accordance with the resolution’s mandate, negotiations on the text of the treaty prohibiting nuclear weapons commenced in March 2017 under the presidency of Ambassador Elayne Whyte Gomez of Costa Rica. Countries who had opposed the movement in the United Nations maintained their stance and boycotted the talks. Proponents of the treaty expected this development, but were prepared to push ahead regardless. Critics argued that this exclusionary approach would effectively render any eventual treaty “useless.” 5 Proponents disagreed, arguing that the treaty would generate normative pressure on the hold-outs by helping to delegitimize nuclear weapons globally.

The drafters of Resolution L.41 specified that substantive decisions on the treaty’s text would be made by two-thirds majority vote. This was in keeping with their philosophy that the process should be “open to all, but blockable by none.” 6 Over 100 civil society organizations also attended the negotiations.

The bulk of the negotiations were completed in a mere three weeks. The final text of the treaty was adopted on July 7, 2017, with 122 votes in favor, one against, and one abstention (recall that most of the treaty’s major opponents did not participate in the conference or vote on the text). The sole “no” vote was cast by the Netherlands, who despite hosting American nuclear weapons on its soil was compelled by its parliament to participate in the negotiations. From day one, the Netherlands made it clear that it would be unable to support a treaty inconsistent with its NATO obligations. As the treaty sought to broadly delegitimize nuclear deterrence, and specifically prohibited stationing and deploying nuclear weapons, its dissenting vote surprised no one.

Singapore was the only country to abstain – it had requested language on the “transit” of nuclear weapons through national territories that had been rejected. 7 Before the vote, many feared that Sweden and Switzerland would also abstain; their capitals had persistent concerns that its formulation legally subordinated the NPT and the CTBT to the new ban. Both ultimately determined that the treaty was, on balance, worth supporting.

What Effects Will the Ban Have?

While only 50 ratifications are needed for the Ban Treaty to enter into force, the diplomats who negotiated the treaty lack the authority to make ratification decisions on behalf of their governments; in democracies, for example, it is the legislative branch that traditionally performs this role. Several countries that voted in favor of the treaty on July 7th – particularly those in the Middle East – are expected not to ratify it, and the United States is already actively pressuring others not to sign. 8

The treaty’s drafters hope it will usher in meaningful normative changes, pressuring the nuclear weapons possessors and umbrella states to disarm more quickly. Critics warn it may undermine nonproliferation and disarmament by creating a “competitor regime,” entangling nonproliferation institutions like the International Atomic Energy Agency or NPT review process in “sterile but contentious debates and disputes over disarmament policy, making it harder for them to do the job the international community needs them to do in preventing nuclear proliferation.” 9 Detractors also argue that the treaty will unwind years of progress in developing the safeguards regime, because it endorses what they see as a lowest-common-denominator system inadequate for confirming that states party are not engaging in the activities prohibited by the ban. Some also warn of ramifications for U.S. military alliances, if states interpret the ban as prohibiting security relations with countries that possess nuclear weapons. Whether the aforementioned positive or negative consequences will materialize remains to be seen. 10 The treaty’s practical and normative implications will only be discernible with time.

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Though there is no agreed-upon legal definition of what disarmament entails within the context of international agreements, a general definition is the process of reducing the quantity and/or capabilities of military weapons and/or military forces.
Entry into force
The moment at which all provisions of a treaty are legally binding on its parties. Every treaty specifies preconditions for its entry into force. For example, the NPT specified that it would enter into force after the United States, the United Kingdom, and the Soviet Union (the Depository governments) and 40 other countries ratified the treaty, an event that occurred on March 5, 1970. See entries for Signature, Ratification.
Ratification: The implementation of the formal process established by a country to legally bind its government to a treaty, such as approval by a parliament. In the United States, treaty ratification requires approval by the president after he or she has received the advice and consent of two-thirds of the Senate. Following ratification, a country submits the requisite legal instrument to the treaty’s depository governments Procedures to ratify a treaty follow its signature.

See entries for Entry into force and Signature.
Comprehensive Nuclear-Test-Ban Treaty (CTBT)
The CTBT: Opened for signature in 1996 at the UN General Assembly, the CTBT prohibits all nuclear testing if it enters into force. The treaty establishes the Comprehensive Test Ban Treaty Organization (CTBTO) to ensure the implementation of its provisions and verify compliance through a global monitoring system upon entry into force. Pending the treaty’s entry into force, the Preparatory Commission of the CTBTO is charged with establishing the International Monitoring System (IMS) and promoting treaty ratifications. CTBT entry into force is contingent on ratification by 44 Annex II states. For additional information, see the CTBT.
Treaty on the Non-Proliferation of Nuclear Weapons (NPT)
The NPT: Signed in 1968, the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is the most widely adhered-to international security agreement. The “three pillars” of the NPT are nuclear disarmament, nonproliferation, and peaceful uses of nuclear energy. Article VI of the NPT commits states possessing nuclear weapons to negotiate in good faith toward halting the arms race and the complete elimination of nuclear weapons. The Treaty stipulates that non-nuclear-weapon states will not seek to acquire nuclear weapons, and will accept International Atomic Energy Agency safeguards on their nuclear activities, while nuclear weapon states commit not to transfer nuclear weapons to other states. All states have a right to the peaceful use of nuclear energy, and should assist one another in its development. The NPT provides for conferences of member states to review treaty implementation at five-year intervals. Initially of a 25-year duration, the NPT was extended indefinitely in 1995. For additional information, see the NPT.
North Atlantic Treaty Organization (NATO)
The North Atlantic Treaty Organization is a military alliance that was formed in 1949 to help deter the Soviet Union from attacking Europe. The Alliance is based on the North Atlantic Treaty, which was signed in Washington on 4 April 1949. The treaty originally created an alliance of 10 European and two North American independent states, but today NATO has 28 members who have committed to maintaining and developing their defense capabilities, to consulting on issues of mutual security concern, and to the principle of collective self-defense. NATO is also engaged in out-of-area security operations, most notably in Afghanistan, where Alliance forces operate alongside other non-NATO countries as part of the International Security Assistance Force (ISAF). For additional information, see NATO.
Nuclear umbrella
See entry for Extended deterrence 
Non-nuclear weapon state (NNWS)
Non-nuclear weapon state (NNWS): Under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), NNWS are states that had not detonated a nuclear device prior to 1 January 1967, and who agree in joining the NPT to refrain from pursuing nuclear weapons (that is, all state parties to the NPT other than the United States, the Soviet Union/Russia, the United Kingdom, France, and China).
The actions of a state or group of states to dissuade a potential adversary from initiating an attack or conflict through the credible threat of retaliation. To be effective, a deterrence strategy should demonstrate to an adversary that the costs of an attack would outweigh any potential gains. See entries for Extended deterrence and nuclear deterrence.
WMD (weapons of mass destruction)
WMD: Typically refers to nuclear, biological, or chemical weapons, though there is some debate as to whether chemical weapons qualify as weapons of “mass destruction.”
Biological weapon (BW)
Biological weapons use microorganisms and natural toxins to produce disease in humans, animals, or plants.  Biological weapons can be derived from: bacteria (anthrax, plague, tularemia); viruses (smallpox, viral hemorrhagic fevers); rickettsia (Q fever and epidemic typhus); biological toxins (botulinum toxin, staphylococcus enterotoxin B); and fungi (San Joaquin Valley fever, mycotoxins). These agents can be deployed as biological weapons when paired with a delivery system, such as a missile or aerosol device.
Chemical Weapon (CW)
The CW: The Organization for the Prohibition of Chemical Weapons defines a chemical weapon as any of the following: 1) a toxic chemical or its precursors; 2) a munition specifically designed to deliver a toxic chemical; or 3) any equipment specifically designed for use with toxic chemicals or munitions. Toxic chemical agents are gaseous, liquid, or solid chemical substances that use their toxic properties to cause death or severe harm to humans, animals, and/or plants. Chemical weapons include blister, nerve, choking, and blood agents, as well as non-lethal incapacitating agents and riot-control agents. Historically, chemical weapons have been the most widely used and widely proliferated weapon of mass destruction.
United Nations General Assembly
The UN General Assembly is the largest body of the United Nations. It includes all member states, but its resolutions are not legally binding. It is responsible for much of the work of the United Nations, including controlling finances, passing resolutions, and electing non-permanent members of the Security Council. It has two subsidiary bodies dealing particularly with security and disarmament: the UN General Assembly Committee on Disarmament and International Security (First Committee); and the UN Disarmament Commission. For additional information, see the UNGA.
Nuclear-weapon states (NWS)
NWS: As defined by Article IX, paragraph 3 of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the five states that detonated a nuclear device prior to 1 January 1967 (China, France, the Soviet Union, the United Kingdom, and the United States). Coincidentally, these five states are also permanent members of the UN Security Council. States that acquired and/or tested nuclear weapons subsequently are not internationally recognized as nuclear-weapon states.
Nonproliferation: Measures to prevent the spread of biological, chemical, and/or nuclear weapons and their delivery systems. See entry for Proliferation.
First Committee
First Committee: The first of six Main Committees of the United Nations General Assembly which deals with all issues related to disarmament and international security. The First Committee on Disarmament and International Security meets every year in October for four to five weeks after the General Assembly’s general debate. See entry for United Nations General Assembly. For additional information, see the NTI Inventory.
Multilateral: Negotiations, agreements or treaties that are concluded among three or more parties, countries, etc.
International Atomic Energy Agency (IAEA)
IAEA: Founded in 1957 and based in Vienna, Austria, the IAEA is an autonomous international organization in the United Nations system. The Agency’s mandate is the promotion of peaceful uses of nuclear energy, technical assistance in this area, and verification that nuclear materials and technology stay in peaceful use. Article III of the Nuclear Non-Proliferation Treaty (NPT) requires non-nuclear weapon states party to the NPT to accept safeguards administered by the IAEA. The IAEA consists of three principal organs: the General Conference (of member states); the Board of Governors; and the Secretariat. For additional information, see the IAEA.
Safeguards: A system of accounting, containment, surveillance, and inspections aimed at verifying that states are in compliance with their treaty obligations concerning the supply, manufacture, and use of civil nuclear materials. The term frequently refers to the safeguards systems maintained by the International Atomic Energy Agency (IAEA) in all nuclear facilities in non-nuclear weapon state parties to the NPT. IAEA safeguards aim to detect the diversion of a significant quantity of nuclear material in a timely manner. However, the term can also refer to, for example, a bilateral agreement between a supplier state and an importer state on the use of a certain nuclear technology.

See entries for Full-scope safeguards, information-driven safeguards, Information Circular 66, and Information Circular 153.


  1. Tim Wright, “Celebration as UN Adopts Historic Nuclear Weapons Ban,” Bulletin of the Atomic Scientists, July 10, 2017,; “Treaty on the Prohibition of Nuclear Weapons,” Ploughshares Fund, July 10, 2017,; Jon Wolfsthal, “The 1st Nuclear Ban Draft is Out,” Arms Control Wonk, May 22, 2017,; Christopher Ford and George Petrovich, “Briefing on Nuclear Ban Treaty,” Carnegie Endowment Events, August 22, 2017,; John A. Bravasco, Opening Statement to the 2017 Session of the United Nations Disarmament Commission, April 3, 2017, New York,
  2. Treaty on the Prohibition of Nuclear Weapons, United Nations General Assembly, July 7, 2017, A/CONF.229/2017/8,
  3. United States Mission to the North Atlantic Treaty Organization Committee on Proliferation, “United States Non-Paper: Defence Impacts of Potential United Nations General Assembly Nuclear Ban Treaty,” October 17, 2016, AC/333-N(2016)0029(INV), retrieved from
  4. Statement by Mikahil I. Uliyanov, Head of the Delegation of the Russian Federation at the First Session of the Preparatory Committee for the 2020 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, May 2, 2017, Vienna, retrieved from
  5. Marie Danielle-Smith, “Opposition seek actions from Liberal foreign policy as Trudeau shuns ‘useless’ disarmament talks,” National Post (Canada), June 7, 2017,
  6. Beatrice Fihn, “Three New Resolutions to Watch Out For at This Year’s Session of the First Committee,” International Campaign to Abolish Nuclear Weapons, October 8, 2015,
  7. Gaukhar Mukhatzhanova, “The Nuclear Weapons Prohibition Treaty: Negotiations and Beyond,” Arms Control Today, September 2017,
  8. Christopher Woody, “Mattis Reportedly Threatened Sweden with Retaliation over Signing a Nuclear Weapons Ban,” Business Insider UK, September 5, 2017,
  9. Christopher Ford and George Petrovich, “Briefing on Nuclear Ban Treaty,” Carnegie Endowment Events, August 22, 2017,
  10. Christopher Ford and George Petrovich, “Briefing on Nuclear Ban Treaty,” Carnegie Endowment Events, August 22, 2017,


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