Treaty on the Prohibition of Nuclear Weapons (2017) — Treaty Brief

Overview

The Treaty on the Prohibition of Nuclear Weapons (TPNW), adopted in 2017 under the auspices of the United Nations, is the first legally binding international agreement to comprehensively prohibit nuclear weapons. It aims to fill a normative gap by outlawing the development, testing, production, acquisition, possession, stockpiling, use, and threat of use of nuclear weapons. The treaty also addresses assistance with prohibited activities and mandates the destruction of existing nuclear arsenals under strict verification measures. Ultimately, the TPNW seeks to delegitimize nuclear weapons and promote their total elimination, complementing existing non-proliferation and disarmament frameworks.

Key obligations

• Prohibition of nuclear weapons activities: States parties must never develop, test, produce, manufacture, otherwise acquire, possess, or stockpile nuclear weapons or other nuclear explosive devices (Article 1).
• Ban on use and threat of use: States parties are prohibited from using or threatening to use nuclear weapons (Article 1).
• Assistance and encouragement: States parties must not assist, encourage, or induce anyone to engage in prohibited activities related to nuclear weapons (Article 1).
• Destruction of nuclear weapons: States possessing nuclear weapons at the time of joining must destroy their arsenals as soon as possible, under effective verification measures (Article 4).
• Environmental remediation: States parties must take necessary measures to remediate environments contaminated by nuclear weapons use or testing (Article 6).
• Victim assistance and environmental remediation: The treaty obliges states to provide adequate assistance to victims of nuclear weapons use and testing, including medical care and rehabilitation (Article 6).
• International cooperation: States parties are encouraged to cooperate in the implementation of the treaty’s provisions, including assistance to victims and environmental remediation (Article 7).
• Verification and compliance: States parties must submit reports on implementation and cooperate with the treaty’s designated bodies to ensure compliance (Articles 5 and 7).

Signatories and status

The TPNW has attracted significant support primarily from non-nuclear-weapon states and civil society actors advocating nuclear disarmament. Many countries from the Global South, as well as some European states, have signed and ratified the treaty, reflecting a growing normative rejection of nuclear weapons. Notably, none of the recognized nuclear-armed states—such as the United States, Russia, China, France, and the United Kingdom—have signed or ratified the treaty, citing concerns over security guarantees and the treaty’s perceived incompatibility with existing nuclear deterrence doctrines. Other NATO members and nuclear umbrella states have also refrained from joining, arguing that the TPNW undermines the established non-proliferation regime centered on the Nuclear Non-Proliferation Treaty (NPT). Ratification patterns reveal a divide between nuclear-armed states and their allies versus the majority of non-nuclear states pushing for a ban.

Major controversies

The TPNW has been subject to several controversies and disputes. One key point of contention is the treaty’s relationship with the NPT. Nuclear-armed states and some allies argue that the TPNW duplicates or undermines the NPT framework, which they consider the cornerstone of global nuclear disarmament and non-proliferation efforts. Another dispute concerns the treaty’s verification and enforcement mechanisms. Critics highlight the absence of a detailed, robust verification regime comparable to that of the International Atomic Energy Agency (IAEA) safeguards under the NPT, raising questions about the feasibility of ensuring compliance, especially regarding disarmament timelines (Article 4). Additionally, the treaty does not provide explicit withdrawal provisions, which has led to debate about the legal and political consequences if a state decides to exit the agreement. Finally, the lack of participation by nuclear-armed states limits the treaty’s practical impact on global nuclear arsenals, leading some to dismiss it as symbolic rather than transformative.

Recent developments

In the years following its adoption, the TPNW has seen incremental progress in terms of ratifications and institutionalization. The treaty entered into force in January 2021 after reaching the required number of ratifications, enabling states parties to begin formal implementation and cooperation. Several states have submitted initial reports on implementation measures, and the first meetings of states parties have focused on establishing the treaty’s secretariat and mechanisms for victim assistance and environmental remediation. Meanwhile, international civil society organizations continue to advocate for broader adoption, emphasizing the humanitarian consequences of nuclear weapons. However, geopolitical tensions and renewed investments in nuclear modernization programs by nuclear-armed states have complicated the treaty’s broader disarmament goals.

Why it matters now

The TPNW remains a critical instrument in the global disarmament landscape by reinforcing the norm that nuclear weapons are unacceptable under any circumstances. As geopolitical rivalries intensify and nuclear modernization accelerates, the treaty provides a platform for non-nuclear states and civil society to pressure nuclear-armed states toward disarmament. Its humanitarian focus and comprehensive prohibitions also contribute to shifting international discourse, making nuclear weapons increasingly stigmatized and politically costly to maintain.