The Treaty on the Prohibition of Nuclear Weapons has grown to dozens of parties and will hold its first review conference in 2026. This forecast explores how far the treaty can reshape nuclear norms, military postures and finance over the next fifty years, and under what conditions a nuclear-armed state might eventually join.
Verdict: Five years after entering into force, the nuclear ban treaty has expanded to several dozen states parties and a larger circle of supportive states, but none possess nuclear weapons (Nuclear Weapons Ban Monitor, 2025-09-26). UN disarmament bodies have set out a review and implementation architecture that will culminate in a first review conference in late 2026 (UN Office for Disarmament Affairs, 2025-03-07). Overall, available evidence supports a trajectory in which the treaty increasingly stigmatizes nuclear weapons, while tangible arsenal reductions depend on parallel strategic negotiations (Toda Peace Institute, 2026-01-22).
Over two decades, the ban treaty's stigma leads several umbrella states to renounce extended nuclear deterrence and join as parties. One smaller nuclear-armed state freezes modernization and undertakes verified reductions under combined NPT and TPNW pressure. Financial and legal constraints make new nuclear-weapon programs politically and economically unattractive, shrinking global arsenals and strengthening non-use norms.
The treaty gradually gains more non-nuclear states, reinforcing a global majority opposing nuclear weapons, but all nuclear-armed states stay outside. Normative pressure influences rhetoric, investment policies and some export controls, yet core deterrence doctrines remain intact. The ban regime functions as a moral and legal reference point while the NPT and bilateral arrangements continue to handle concrete arms-control obligations.
Great-power rivalry and regional crises drive rearmament and modernization, while nuclear-armed states dismiss the ban treaty as irrelevant. Diverging expectations between ban supporters and deterrence-dependent allies deepen diplomatic rifts inside alliances. A breakdown of existing arms-control agreements leaves the TPNW symbolically important but practically sidelined as arsenals grow and alert postures harden.
A close call or limited use of a nuclear weapon triggers global outrage and a surge of support for the ban treaty, including from one or more umbrella states. Alternatively, a breakthrough in strategic stability technology or missile defense reduces perceived reliance on nuclear weapons. Either shock could rapidly shift the political calculus around accession in ways that are hard to model from today's vantage point.
Developments: By late 2025 the ban treaty has 74 states parties and 25 signatories, representing a clear majority of non-nuclear states.([banmonitor.org](https://banmonitor.org/tpnw-status?utm_source=openai)) Preparations advance for the first TPNW Review Conference in late 2026, with South Africa as president and working groups on universalization and victim assistance.([disarmament.unoda.org](https://disarmament.unoda.org/en/our-work/weapons-mass-destruction/nuclear-weapons/treaty-prohibition-nuclear-weapons?utm_source=openai)) In parallel, planning continues for the 2026 NPT Review Conference, where states parties will debate strategic stability, modernization and the relationship between the two treaties.([meetings.unoda.org](https://meetings.unoda.org/npt-revcon/treaty-on-the-non-proliferation-of-nuclear-weapons-eleventh-review-conference-2026?utm_source=openai))
Risks: Heightened great-power tensions could spill into disarmament forums, producing deadlocked conferences and bruising diplomatic disputes. Ban supporters may push maximalist language that alienates nuclear-reliant allies, while deterrence advocates might underplay humanitarian concerns. A failed or acrimonious review cycle would undermine confidence in multilateral arms control more broadly.
Outlook: The likely outcome is incremental progress on implementation details and victim assistance, but limited convergence on core deterrence questions. Both supporters and opponents of the ban treaty entrench their narratives. Near-term strategic risk levels remain driven more by bilateral and regional dynamics than by treaty forums.
Developments: The 2026 review meetings crystallize two partially overlapping coalitions: one centered on deterrence and strategic stability, another on prohibition and humanitarian law. Some states attempt to bridge the gap by emphasizing risk reduction, de-alerting and transparency measures that are compatible with both frameworks. Civil society campaigns intensify pressure on financial institutions and cities to adopt nuclear-weapon-free policies regardless of national positions.
Risks: If review conferences end without meaningful joint action plans, publics may become cynical about disarmament promises and turn attention elsewhere. Nuclear-armed states could retaliate against ban supporters by reducing security cooperation or aid, politicizing the regime. Misperceptions about each side's red lines might hinder future compromise on practical risk-reduction steps.
Outlook: Over two years, normative contestation is sharp but manageable, with most governments keeping channels open. The ban treaty's legal force for its parties grows, yet its direct impact on arsenals remains minimal. Strategic stability remains fragile, so the value of normative advances depends on whether they eventually inform concrete arms-control proposals.
Developments: Within three years, TPNW parties refine reporting, verification assistance and victim-support mechanisms, potentially creating an international trust fund. Conferences of parties institutionalize interactions among humanitarian, environmental and disarmament communities. Some non-nuclear states integrate ban obligations into national legislation, affecting procurement and investment policies even in dual-use sectors.
Risks: An overemphasis on institutional process could mask a lack of progress on actual risk reduction, breeding frustration among activists and vulnerable communities. Nuclear-armed states may respond with parallel institutions that reinforce their own norms, deepening regime fragmentation. Budget constraints and political turnover might weaken follow-through on ambitious assistance commitments.
Outlook: The likeliest picture is of a more structured ban regime that has stronger internal coherence but limited external leverage. Symbolic and financial impacts on the nuclear enterprise grow slowly yet remain secondary to hard security calculations. The treaty's future influence will hinge on whether it can connect institutional work to concrete steps by nuclear-reliant states.
Developments: Over five years, more pension funds, insurers and banks may adopt policies restricting investment in nuclear-weapon producers or associated infrastructure. City-level initiatives and regional nuclear-weapon-free zones increasingly reference the ban treaty, strengthening subnational pressure on national governments. Within alliances, debates over hosting nuclear forces, sharing arrangements and declaratory policy incorporate humanitarian and legal arguments shaped by TPNW advocacy.
Risks: Financial restrictions might be partial or inconsistent, limiting material impact on major contractors and reinforcing perceptions of greenwashing. Intra-alliance tensions over nuclear sharing could be exploited by adversaries or fuel domestic polarization. A significant crisis involving a nuclear-armed state might lead governments to prioritize deterrence messages, sidelining humanitarian frames.
Outlook: The baseline expectation is moderate normative and financial pressure that nudges, but does not transform, alliance nuclear policies. Some visible wins in divestment and local politics will coexist with continued modernization of arsenals. Whether the treaty shifts decisive behavior will depend on political shocks and leadership choices in key capitals.
Developments: A decade from now, the interplay between the ban treaty, NPT processes and regional security arrangements will be clearer. In a more cooperative world, states may use the ban's norms to justify new ceilings, de-alerting steps or no-first-use declarations. In a more competitive setting, the treaty could remain a rallying point for non-aligned states and civil society while nuclear powers pursue advanced delivery systems and warhead types.
Risks: Technological advances such as hypersonic delivery, dual-capable systems and autonomous platforms may compress decision times, raising accidental-use risks regardless of normative commitments. If the ban treaty is seen as having failed to change trajectories, support could stagnate or erode. Conversely, if it is blamed for undermining deterrence, some governments might distance themselves from its supporters in other policy areas.
Outlook: On current evidence, both benign and adverse paths remain plausible, with a slight tilt toward continued reliance on deterrence under growing normative scrutiny. The ban treaty is unlikely to be the primary driver of strategic outcomes but will shape the language and legitimacy of policy options. Its importance will be judged by whether it meaningfully reduces the probability or severity of nuclear use over time.
Developments: Over twenty years, internal politics or regional breakthroughs might prompt at least one nuclear-armed state to explore observer status, partial alignment or conditional commitments linked to the ban treaty. Transitional arrangements could emerge, such as legally binding negative security assurances to TPNW parties or limited decommissioning paired with verification experiments. Historical analogies from chemical and biological weapons conventions could inform pathways from stigmatization to prohibition.
Risks: Regime fragmentation remains a major danger; incompatible legal commitments could complicate future comprehensive agreements. A new entrant to the nuclear club or a cascade of proliferation would undermine the treaty's central non-proliferation narrative. Persistent inequalities in how humanitarian and environmental harms are addressed may reduce credibility among affected communities.
Outlook: The most defensible forecast is that at least some nuclear-armed states will adjust rhetoric and peripheral policies in response to the ban, even if they do not join. Concrete disarmament steps remain contingent on broader security bargains and technological trends. The treaty's long-run legacy will depend on how well it integrates justice for victims with credible pathways to arsenal reductions.
Developments: Across fifty years, the ban treaty could either be a cornerstone of a near-universal prohibition regime or a historical artifact from an era of unrealized idealism. In an optimistic trajectory, successive generations normalize the idea that nuclear weapons are illegitimate, and multilateral agreements gradually codify verified disarmament. In a pessimistic trajectory, recurring crises entrench nuclear deterrence as a permanent feature of international security, relegating the TPNW to a minority position.
Risks: Predicting century-scale security outcomes is fraught; unknown technologies, climate stresses and geopolitical realignments could alter incentives in ways difficult to anticipate. A major nuclear conflict, even if limited, would rewrite assumptions about deterrence, stability and the role of legal norms. Alternatively, a very long period without nuclear use might induce complacency and underinvestment in verification and enforcement.
Outlook: Given deep uncertainty, the central expectation is that the treaty will meaningfully influence norms but only partially shape arsenals. Its success will be measured by whether it helps keep nuclear weapons from being used, accelerates reductions and provides justice to affected communities. Even in the best case, it will operate alongside, not replace, other pillars of global security governance.