The Third Meeting of States Parties (3MSP) to the Treaty on the Prohibition of Nuclear Weapons (TPNW) took place at the United Nations headquarters in New York City March 3-7. A large and diverse group of stakeholders convened, including 86 countries and over a thousand representatives from 163 civil society organizations. The week included rich discussions in plenary sessions and numerous side events hosted by state delegations and civil society groups. 

The treaty, which entered into force in 2021, is the first to place a full ban on the possession, use, or testing of nuclear weapons. With 73 states parties and 94 signatories, the treaty is now just one country shy of a global majority. A unique aspect of the treaty that sets it apart from other nuclear weapons agreements is its emphasis on humanitarian and environmental impacts of nuclear weapons and centering of affected community voices. The 3MSP, for example, was presided over by Kazakhstan, whose environment and citizens have been affected by Russian nuclear explosive tests.

The 3MSP took place at a time of increased geopolitical and historical significance. The final political declaration adopted at the conclusion of the week noted the increasing risk of nuclear war, with growing nuclear arsenals, modernization programs, and nuclear saber rattling around the world. This year also marks the 80th anniversary of the first testing and use of nuclear weapons – and relatedly, FAS’s founding. 

Welcomed Advancements of the Past Year

Over the past year, the campaign to abolish nuclear weapons has experienced numerous wins that were celebrated at the Meeting of State Parties. New ratifications of the treaty by Indonesia, São Tomé and Príncipe, Sierra Leone, and Solomon Islands brought the number of states parties to just one shy of a global majority. During the intersessional period, working groups established in the Vienna Action Plan and further strengthened at 2MSP continued work on universalization, establishing an international trust fund for research and medical compensation for affected communities, and creating verification measures for states to disarm.

Possibly the most well-earned achievement of the year came from Nihon Hidankyo, a Japanese organization of survivors of the atomic bombings of Hiroshima and Nagasaki (known as “Hibakusha”), which won the 2024 Nobel Peace Prize for advocating against nuclear weapons use through personal testimony. Nihon Hidankyo has long supported the TPNW, and several members were in attendance at the 3MSP to share their stories at side events, stand in solidarity with other affected communities, and support the treaty’s implementation.

Other United Nations actions this year worked towards a world free from nuclear weapons. The UN General Assembly Resolution for a new scientific study on the consequences of nuclear war passed with 136 votes in favor, 3 against and 29 abstentions. The resolution’s call for researching climatic, environmental, and health consequences aligns with the TPNW’s focus on humanitarian consequences of nuclear war. The overwhelming majority of global states voting in favor of the resolution also indicated a motivation by non-nuclear states for a world without nuclear weapons. The UN Summit of the Future also reaffirmed the call for disarmament in its Pact for the Future.

Concerning Developments

In recent years, geopolitical tensions and disruptive technologies have heightened the risk of nuclear war. In January, the Bulletin of the Atomic Scientists moved the Doomsday Clock closer to midnight; at 89 seconds, the clock is the closest it has ever been to the metaphorical apocalypse. Every single nuclear-armed state is advancing their nuclear forces in number or in capabilities.

The Trump administration has proposed new costly military programs like the Iron Dome missile defense system. The program could spur additional Chinese and Russia nuclear buildup as they ensure deterrence capabilities that are designed to outsmart the missile defense system. In addition, the administration’s seeming abandonment of allies have led to a call by some European and Asian state leaders to increase defense spending and consider the development of their own nuclear weapons.

In general, the global appetite for arms control and nonproliferation has decreased. There have been no clear moves to revitalize the New START treaty since Russia suspended its participation in 2023. U.S. efforts to engage in risk reduction talks with China have also not been successful as China is not convinced nuclear arms control is in their security interests. There does not appear to be any efforts between the United States and Russia to negotiate a follow-on treaty to New START, which expires in February 2026 and is the last remaining treaty constraining the deployed arsenals of the two largest nuclear powers. The past two Nonproliferation Treaty Review Conferences have failed to reach final consensus documents. Combined with the reduction in diplomatic efforts between nuclear states, emerging technologies like artificial intelligence create instability and an increased risk of miscalculation or misunderstanding that could lead to nuclear use.

States demonstrated their increased reliance on nuclear weapons in their military strategy through spending, rhetoric, and exercises in 2024. For example, ICAN’s Global Nuclear Weapons Spending report published in 2024 found that in 2023 the nine nuclear weapons states spent 91.4 billion on nuclear weapons, an increase of 13.4 % from the previous year, and projected that 2024 spending would surpass $100 billion.

3MSP Discussions and Decisions

The international trust fund for affected communities was a topic of much discussion at the Meeting. Communities in the Pacific island nations, Kazakhstan and the continental United States face many illnesses and health complications from radioactive fallout from explosive nuclear testing. From 1949 to 1989, the Soviet Union conducted about 456 nuclear tests near the Kazakh city of Semey, resulting in birth defects, a multitude of cancers, and immune disorders in generations of nearby residents. The United States, United Kingdom, and France conducted 318 tests across the Pacific, causing environmental damage, forcibly displacing communities, and health consequences. The United States conducted an additional 928 tests on the continental United states, irradiating residents across the West. The purpose of the international trust fund will be to fund community health studies related to nuclear weapons impacts that will inform humanitarian assistance subsequently provided by the fund. The working group in charge of planning and preparing the fund will also provide a report no later than four months before the first review conference of the TPNW on the technical provisions for the fund. 

The 3MSP decided that the first review conference for the Treaty will be held in New York City November 30–December 4, 2026 with South Africa presiding. Before then, states expect productive work again in the intersessional period. This will include work on the universalization of the treaty, led by Austria, New Zealand, and Uruguay; victim assistance and environmental remediation again led by Kazakhstan and Kiribati; and the creation of an international authority for verification led by Malaysia and the Philippines.

Representatives and allies of communities affected by uranium mining and milling expressed concerns that the TPNW preamble text which protects “the research, production, and use of nuclear energy for peaceful purposes” is in contention with providing full nuclear justice and prevents trust fund compensation to all affected communities.

A working paper submitted by 44 civil society organizations expressed that nuclear technologies from “cradle to grave” impact public health and the environment. Noting that uranium mining and milling overwhelmingly occurs on indigenous lands, the groups advocated for the acknowledgement that all nuclear technologies, due to the requisite uranium resources, have the potential to cause contamination to environments and negative health consequences.

Both Marshall Islands official state and civil society representatives also called for structural changes within the treaty. The Marshall Islands, where the United States conducted over 33 nuclear explosive tests, are severely contaminated by radioactive fallout, resulting in high rates of health issues like cancers, birth defects, and immune disorders among the population and forced displacement of residents as the fallout relegated certain areas uninhabitable. The Marshall Islands support the efforts of the TPNW, but have not ratified the treaty. 

The delegation from the Marshall Islands argued that the language in Article 6 of the treaty does not adequately place burden on the United States for environmental remediation for nuclear testing. In his statement, the Marshallese Ambassador said the TPNW “wrongfully absolves responsibility for the consequences of nuclear weapons testing from those states which conducted the nuclear testing. And instead leaves us responsible to pay for billions of dollars of adjudicated impacts which we did not choose.” While states that support the treaty do stand in solidarity with each other, they do not have monolithic views about the correct implementation or structure.

Many of the working papers written by affected communities also call for the international trust fund to be open to non-state parties, which would increase engagement with the treaty and open opportunities for further compensation to impacted communities.

Numerous side events featured a coalition of affected communities in an impressive show of solidarity. For example, the Bikini Day Side Event: “Damage of Nuclear Weapons and Urgent Need for Relief – Nuclear Sufferers Speak,” featured Japanese and Korean Survivors of the Hiroshima and Nagasaki bombings, Pacific island communities affected by nuclear testing, Marshall Islanders, and Gilbertese representatives. While originally the term “hibakusha” translated in Japanese to bomb-affected people and referred specifically to survivors from Hiroshima and Nagasaki, this term has been widely shared with and adopted by other impacted communities. Regardless of whether it was Japanese bomb survivors or downwinders from tests before and after, both communities share the pain of a bomb dropping on their land. The solidarity and respect to all affected populations and generations demonstrates the dedication to a united front for a world without nuclear weapons. 

As 2025 is the 80th year since the U.S. bombing of Hiroshima and Nagasaki, many of the original atomic bomb survivors have since passed. While many within the Hibakusha community worried that future generations would be too preoccupied with other issues like the economy and climate change to continue advocating for a world without nuclear weapons, there remains a strong and vibrant youth movement against the bomb that carries forward on the testimony of survivors. During the Youth for TPNW side event, youth delegates heard from a Hibakusha who was just 2 years old when the United States dropped an atomic bomb on her hometown of Nagasaki. She said, “today’s listeners are tomorrow’s storytellers.” 

The 2nd Meeting of States Parties (MSP) to the Treaty on the Prohibition of Nuclear Weapons (TPNW) took place at United Nations Headquarters in New York City from November 27 through December 1. Participants in the Meeting included 59 member nations, 35 observer states, around 700 civil society registrants, members of the scientific community, and representatives of communities affected by nuclear weapons. 

The Meeting culminated in agreement by states parties on a joint declaration and package of decisions. Arguably, the most significant outcome of the 2nd MSP was the consensus joint declaration challenging long-held assumptions of nuclear deterrence theory and affirming the security risks it poses.

What’s happened since the first MSP

The first Meeting of States Parties to the TPNW occurred in Vienna, Austria in June 2022, where states parties adopted the Vienna Action Plan. That plan listed 50 actions for States Parties to implement the TPNW and goal of global nuclear disarmament and created three working groups on disarmament verification; victim assistance, environmental remediation, and international cooperation and assistance; and universalisation. The Vienna Plan additionally created thematic focal points for gender and complementarity of the TPNW with other fora like the Nuclear Non-Proliferation Treaty (NPT). The working groups each met several times during the intersessional period.

The first MSP also created a Scientific Advisory Group (SAG) of 15 experts to study and provide scientific and technical expertise on a variety of issues related to nuclear weapons. The SAG is the first international scientific body formally created by a multilateral treaty process to promote nuclear disarmament. The group met nine times during the intersessional period to prepare its report to the second MSP, and its final report drew heavily upon research conducted by independent open-source analysts, including the Federation of American Scientists. 

Several states have joined or taken action toward joining the treaty during the intersessional period. The Bahamas, Barbados, Burkina Faso, Djibouti, Equatorial Guinea, Haiti, and Sierra Leone signed the treaty; the Dominican Republic, Democratic Republic of the Congo, and Malawi ratified the treaty; Sri Lanka acceded to the treaty; and Indonesia, the fourth largest country in the world by population, recently enacted the TPNW into law within its parliament and is expected to soon complete ratification.

Nearly half of NPT states parties have now signed the TPNW, reflecting growing unacceptance of the lack of progress on nuclear weapons states’ Article VI disarmament obligations.

Noteworthy happenings during 2MSP

The 2nd Meeting of States Parties included a large number of national and other statements and reports. The proceedings notably included moving testimony from nuclear-affected communities, active participation and presentation of research by civil society, a report from the Scientific Advisory Group, notable observer state attendance, and statements from a group of parliamentarians from around the world and the financial community. 

Impacted communities

One of the most important features of the TPNW is its focus on impacted communities. Participants and attendees included victims of nuclear testing in Kazakhstan, Kiribati, Marshall Islands, Australia, and French Polynesia; Hibakusha (atomic bomb survivors) from Hiroshima and Nagasaki; downwinders from the U.S. Southwest; and communities impacted by uranium mining. 

Benetick Kabua Maddison, Executive Director of the Marshallese Education Initiative, delivered a joint statement to the Meeting on behalf of 26 affected community organizations and supported by 45 allied organizations that provided testimony of the harm of nuclear weapons and called for land remediation and universalization of the treaty.

Scientific Advisory Group 

In addition to numerous civil society research presentations and statements throughout the week, the Scientific Advisory Group (SAG) presented its Report on the Status and Developments Regarding Nuclear Weapons to the Meeting. This presentation marked the first formal participation of the SAG in the proceedings of the TPNW following its formation.

SAG co-chairs Dr. Zia Mian and Dr. Patricia Lewis introduced the report to the MSP. The report, heavily citing the work of FAS’s Nuclear Information Project, included an overview of the global status of nuclear stockpiles, nuclear modernization, nuclear risks, humanitarian consequences, and disarmament verification. Additionally, the SAG recommended a global scientific study sponsored by the UN on the effects and consequences of nuclear war. 

Observer states

Unsurprisingly, none of the nuclear-armed states attended, but several U.S. treaty allies – Australia, Belgium, Germany, and Norway – attended the MSP as observers. Two of the observers (Belgium and Germany) are part of the NATO nuclear sharing arrangements to deliver U.S. nuclear weapons in times of war.  

The delegate from Norway made a statement in support of NATO as a nuclear alliance: “Norway stands fully behind NATO’s nuclear deterrence and posture, including the established nuclear sharing arrangements.” According to some analysts, this may be the first time Norway has explicitly supported U.S. nuclear weapons deployments in Europe in a multilateral disarmament forum. This continues a trend of increased support of NATO nuclear missions by Norway since the end of the Cold War, which has recently included participating in joint exercises with US B-52 bombers and a US B-2 bomber landing in Norway for the first time.

The German delegation similarly supported NATO’s nuclear mission in its statement to the Meeting while criticizing Russia’s announcement of nuclear weapons deployments to Belarus. The representative stated that “confronted with an openly aggressive Russia, the importance of nuclear deterrence has increased for many states, including for my country.”

Three observer states to the first MSP were notably absent from the second: The Netherlands, Finland, and Sweden. The Netherlands is the only NATO member to participate in the initial negotiations of the TPNW. Despite this, the Netherlands has consistently voted against UNGA resolutions welcoming the adoption of the TPNW, and, after the first MSP, the Dutch Foreign Ministry reported that continued observation of TPNW proceedings “is not useful.” 

Finland voted against the UNGA resolution on the TPNW for the first time in 2022 and chose not to observe the 2nd MSP, possibly due to its recent NATO membership. Sweden similarly voted against the resolution for the first time in 2022 and was absent from the 2nd MSP. These actions by Sweden could be related to its bid for NATO membership and its brand new Defense Cooperation Agreement with the U.S.

Points of tension

Although states parties came to agreement on a final declaration and package of decisions (with the MSP even closing around two hours earlier than scheduled on the final day), there were some points of disagreement and division throughout the week. 

One primary disagreement was on nuclear sharing – particularly how strongly the final declaration should condemn it. European states parties pushed back on forceful language to prevent their regional allies and the U.S. from being implicated in the condemnation that they wanted centered on Russia’s nuclear deployments to Belarus. The final joint declaration avoided mention of specific sharing arrangements and simply included a condemnation of and call to cease all such arrangements.

In a similar vein, some states like South Africa wanted to include strong language on the Comprehensive Test Ban Treaty (CTBT) that would condemn both Russia’s recent de-ratification and the fact that the U.S. has never ratified the CTBT. U.S. allies at the Meeting, however, wanted language focusing solely on Russia’s actions. Ultimately, neither country was identified by name in the joint declaration; instead, states parties made a broad call for all countries to sign and ratify the CTBT and promote its entry into force.

Unique participants 

Alongside states parties, observer states, and civil society groups, the TPNW 2MSP included participation from a diverse, global group of parliamentarians as well as representatives from the financial community. 

A delegation of 23 parliamentarians from 14 different countries, including US Rep. Jim McGovern (D-MA), delivered a statement to the Meeting urging governments (in some cases their own) to join the treaty. 

The financial community provided a statement to the MSP on behalf of over 90 investors to promote collaboration between states parties and the financial community to divest from the nuclear weapons industry.

Results of the MSP: Final declaration and decisions

The Meeting of States Parties closed on Friday, December 1st around 4:30 PM after consensus agreement on a joint declaration and package of decisions. 

Through the joint declaration, states presented their consensus view that nuclear risks are growing due to the actions of nuclear weapons states: “Nuclear risks are being exacerbated in particular by the continued and increasing salience of and emphasis on nuclear weapons in military postures and doctrines, coupled with the on-going qualitative modernization and quantitative increases in nuclear arsenals, and the heightening of tensions.” 

States parties additionally declared the catastrophic humanitarian effects of nuclear weapons as the central impetus for pursuing and achieving global nuclear disarmament, spotlighting the human and environmental costs to argue that “the only guarantee against the use of nuclear weapons is their complete elimination and the legally binding assurance that they will never be developed again.” States jointly rejected any normalization of nuclear rhetoric and identified nuclear threats and deterrence as security risks, declaring:

“The threat of inflicting mass destruction runs counter to the legitimate security interests of humanity as a whole. This is a dangerous, misguided and unacceptable approach to security… Far from preserving peace and security, nuclear weapons are used as instruments of policy, linked to coercion, intimidation and heightening of tensions. The renewed advocacy, insistence on and attempts to justify nuclear deterrence as a legitimate security doctrine gives false credence to the value of nuclear weapons for national security and dangerously increases the risk of horizontal and vertical nuclear proliferation… The perpetuation and implementation of nuclear deterrence in military and security concepts, doctrines and policies not only erodes and contradicts nonproliferation, but also obstructs progress towards nuclear disarmament.”

On nuclear sharing, states parties called on all states with nuclear arrangements, including extended nuclear security guarantees, to cease all such arrangements and join the TPNW. They also reaffirmed the complementarity between the TPNW and the NPT and called out the lack of progress nuclear weapons states have made toward their NPT Article VI obligations on disarmament. 

The package of decisions included an agreement by states parties to collaborate in challenging false narratives of nuclear deterrence by engaging in and promoting scientific work on the humanitarian consequences of nuclear weapons. This collaboration includes the establishment of a consultative process on security concerns of states to advance arguments against nuclear weapons and nuclear deterrence. 

States also agreed to engage in discussions on establishing an international trust fund for victim assistance and environmental remediation. Lack of progress and vague phrasing on such a trust fund is likely due to disagreements on whether or not non-states parties to the TPNW should be able to contribute to the fund. Some states fear non-states parties could use their contributions to the trust fund to avoid strong pressure to join the treaty. 

Next steps for the intersessional period

The Third Meeting of States Parties to the treaty will take place in 2025 from March 3 to 7, again in New York. 

During the intersessional period, the informal working groups established by the Vienna Action Plan will continue to meet, and focused discussions will take place in order to present a report to the third MSP on the feasibility and guidelines for an international trust fund. 

States parties and signatories will engage in an intersessional consultative process along with the Scientific Advisory Group, International Committee of the Red Cross (ICRC), International Campaign to Abolish Nuclear Weapons (ICAN), and others with the aim of providing a report to the third MSP containing arguments and recommendations to promote a counternarrative to nuclear deterrence rhetoric.