United Kingdom
The United Kingdom has the world's fifth largest nuclear arsenal. Along with all other nuclear-armed states, the United Kingdom boycotted the negotiations on the Treaty on the Prohibition of Nuclear Weapons (TPNW) in 2017. Since then, it has consistently voted against the annual UN General Assembly resolutions on the Treaty, including in 2024. It may sign and ratify the TPNW at any time but will have to destroy its nuclear weapons in accordance with a legally binding, time-bound plan and make other changes to its policies and practices to become compliant.
TPNW Status
| Nuclear warhead inventory at the beginning of 2025 | ||
|---|---|---|
| Total inventory of warheads | 225 | |
| Retired warheads | 0 | |
| Warheads available for use | 225 | |
| Estimated yield (MT) | 22.5 | |
| Hiroshima-bomb equivalents | 1500 | |
| Key weapons of mass destruction treaties | ||
|---|---|---|
| NUCLEAR WEAPONS | ||
| Party to the TPNW | No | |
| Party to the NPT | Yes (Ratified 1968) | |
| Ratified the CTBT | Yes (Ratified 1998, Annex 2 state) | |
| Party to an NWFZ | No (4 of 5 NSA protocols) | |
| CSA with the IAEA | Voluntary offer agreement | |
| AP with the IAEA | Partial (In force 2004) | |
| BIOLOGICAL AND CHEMICAL WEAPONS | ||
| Party to the BWC | Yes (Ratified 1975) | |
| Party to the CWC | Yes (Ratified 1996) | |
| TPNW Art. 1(1) prohibitions: Compatibility in 2024 | ||
|---|---|---|
| (a) | Develop, produce, manufacture, acquire | Non-compatible |
| Possess or stockpile | Non-compatible | |
| Test | Compatible | |
| (b) | Transfer | Compatible |
| (c) | Receive transfer or control | Non-compatible |
| (d) | Use | Compatible |
| Threaten to use | Compatible | |
| (e) | Assist, encourage or induce | Non-compatible |
| (f) | Seek or receive assistance | Non-compatible |
| (g) | Allow stationing, installation, deployment | Non-compatible |
| TPNW voting and participation | |
|---|---|
| UNGA resolution on TPNW (latest vote) | Voted no (2024) |
| Participated in 2MSP (2023) | No |
| Participated in 1MSP (2022) | No |
| Average MSP delegation size (% women) | N/A |
| Adoption of TPNW (7 July 2017) | N/A |
| Participated in TPNW negotiations (2017) | No |
| Negotiation mandate (A/RES/71/258) | Voted no |
| Fissile material | |
|---|---|
| Nuclear facilities | Yes |
| Fissile material production | Yes (Civilian) |
| HEU stocks | 23 Mt (22 Mt available for weapons) |
| Plutonium stocks | 119.6 Mt (3.2 Mt available for weapons) |
| SQP with the IAEA | N/A |
Latest developments
During the high-level segment of the UN General Assembly in September 2024, the Prime Minister of the United Kingdom, Keir Starmer, called on states to ‘work together to make the world less dangerous’. ‘The entire framework of arms control and counter-proliferation painstakingly constructed over decades has begun to fall away,’ he said.1
In April 2024, prior to becoming Prime Minister, Starmer wrote in a newspaper commentary: ‘My commitment to NATO and the UK’s nuclear deterrent – maintained on behalf of NATO allies – is unshakeable. Absolute. Total.’ He described the UK’s development of nuclear weapons in the 1950s as a ‘towering achievement’ that ‘defined modern Britain’, and he pledged to build all four planned Dreadnought-class nuclear-armed submarines to replace the current Vanguard-class fleet.2 In an interview with the BBC, he declared his willingness to use nuclear weapons if elected.3
In the First Committee of the UN General Assembly in November 2024, the United Kingdom, France, and the United States reiterated their opposition to the TPNW. ‘Our three countries do not consider the TPNW to be an effective disarmament measure,’ they said in a joint statement. ‘We stress that the TPNW does not change the legal obligations on our countries with respect to nuclear weapons. We do not accept any arguments that the TPNW reflects or in any way contributes to the development of customary international law.’4
At the same meeting, the United Kingdom said in a national statement that ‘for as long as others have nuclear weapons, the UK will maintain a nuclear deterrent. Our posture of minimum credible nuclear deterrence, assigned to the defence of NATO, is a vital safeguard for the UK, our allies, and for maintaining global peace and security.’5
All of the United Kingdom's nuclear weapons are currently based in Scotland, where political support for the abolition of nuclear weapons is strong. In March 2024, the Scottish government said that ‘nuclear weapons should not be based in Scotland and should be removed from Scotland in the safest and most expeditious manner possible following independence’.6
Recommendations
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The United Kingdom should acknowledge that nuclear deterrence is not a sustainable solution for its own or international security, and that any perceived benefits are far outweighed by the risk of nuclear accidents or war.
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The United Kingdom should comply with its existing obligation under Article VI of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), and pursue negotiations in good faith on nuclear disarmament.
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The United Kingdom should urgently adhere to the TPNW. Until it is in a position to do so, it should welcome the TPNW as a valuable component in the global disarmament and non-proliferation architecture, work with the Treaty's states parties on practical steps towards disarmament, and attend the meetings of states parties as an observer.