What It Means in Practice
The Treaty on the Prohibition of Nuclear Weapons (TPNW) is a 2017 multilateral treaty that prohibits the development, testing, production, manufacture, acquisition, possession, stockpiling, transfer, hosting, threat of use, and use of nuclear weapons. It was opened for signature in September 2017 and entered into force on 22 January 2021 after 50 ratifications were deposited.
The treaty is the first legally binding international agreement to comprehensively prohibit nuclear weapons. Article 1 of the TPNW lays out the prohibitions; Article 4 covers a process for nuclear-armed states to join and disarm; Article 5 addresses cooperation with states that host or station foreign nuclear weapons.
Why It Matters
The TPNW emerged from frustration with the slow pace of under the . For decades, non-nuclear-weapon states had argued that the NPT's Article VI disarmament obligation was being ignored by the nuclear powers. The TPNW represents the non-nuclear majority's attempt to create normative pressure for disarmament outside the NPT . The campaign that produced it — the International Campaign to Abolish Nuclear Weapons (ICAN) — won the 2017 Nobel Peace Prize.
The treaty matters as a stigmatization instrument even if it lacks the participation that would give it disarmament effect. Major banks and pension funds have divested from nuclear-weapon producers citing TPNW norms; cities have passed resolutions endorsing it; uses it as a benchmark.
The Membership Gap
No nuclear-armed state has joined or supports the TPNW. All five NPT-recognized nuclear powers (US, UK, France, Russia, China) plus India, Pakistan, Israel, and North Korea stayed out. All allies stayed out under US pressure. Japan and South Korea — both under the US — stayed out for the same reason.
The TPNW's signatories are predominantly states. As of 2026, the treaty has 73 ratifications and 95 signatures. The membership gap is the central limitation of the regime: a prohibition treaty without the -holders cannot directly disarm.
TPNW vs NPT
Proponents argue the TPNW complements the NPT by strengthening the norm against nuclear weapons. Critics including all P5 states argue the TPNW is counterproductive — it divides the disarmament community, undermines NPT processes, and offers a parallel forum where rigorous verification and step-by-step measures are less prominent. The TPNW's text deliberately leaves verification, baseline declarations, and irreversibility provisions thinner than NPT-era arms control because the signatories don't possess weapons to verify.
Common Misconceptions
The TPNW does not 'ban' nuclear weapons globally — it binds only its signatories, none of whom possess nuclear weapons. The binding effect on possessor states is zero unless they join.
Another misconception is that the TPNW supersedes the NPT. It does not — the two coexist as separate treaties, with the NPT remaining the dominant nonproliferation instrument.
Real-World Examples
The First Meeting of States Parties (Vienna, June 2022) issued the Vienna Declaration condemning Russian nuclear threats during the Ukraine war. The Second Meeting (New York, November 2023) extended work on victim assistance and environmental remediation for nuclear-test-affected communities. The Norwegian government — a NATO member — has attended TPNW meetings as an observer, a small but politically meaningful crack in the alliance's TPNW boycott.
Example
Austria's 2024 hosting of the Third Meeting of TPNW States Parties produced declarations on victim assistance and environmental remediation, demonstrating the treaty's continuing political momentum despite nuclear-state non-participation.