UK Nuclear Warhead Increase Media Backgrounder


For immediate release. Geneva, 15 March 2021.

UK to increase nuclear warhead cap in integrated review of defence and foreign policy 


  • The latest UK defence strategic review, to be released on 16 March, will reportedly increase the 180 nuclear warhead target cap for the mid 2020s set in the last review to 260 warheads, above the current UK stockpile of 215 warheads.
  • Nuclear weapons are unpopular in the United Kingdom where the majority of public opinion, many cities and members of parliament are calling on the government to join the Treaty on the Prohibition of Nuclear Weapons (TPNW).
  • A move to increase nuclear weapons by the United Kingdom would be in direct defiance of its commitment under Article VI of the Nuclear Non-Proliferation Treaty to pursue disarmament.
  • The UK is going in the wrong direction. With the Treaty on the Prohibition of Nuclear Weapons entering into force early this year, nuclear weapons are illegal under international law. The UK decision to increase its nuclear weapon limit stands in stark contrast to this international norm.

Beatrice Fihn, Executive Director of ICAN, said about the decision:

“A decision by the United Kingdom to increase its stockpile of weapons of mass destruction in the middle of a pandemic is irresponsible, dangerous and violates international law. While the British people are struggling to cope with the pandemic, an economic crisis, violence against women, and racism, the government choses to increase insecurity and threats in the world. This is toxic masculinity on display.”

“While the majority of the world’s nations are leading the way to a safer future without nuclear weapons by joining the Treaty on the Prohibition of Nuclear Weapons, the United Kingdom is pushing for a dangerous new nuclear arms race.”

Current UK Nuclear Arsenal

The Stockholm International Peace Research Institute estimates that as of January 2020, the United Kingdom possessed 215 nuclear warheads. UK nuclear warheads are launched from missiles on submarines. The UK has four submarines that can carry nuclear-warhead equipped missiles. When not on patrol, the submarines are docked off the coast of Scotland.

The UK is currently building new nuclear-capable submarines to replace its current fleet, which it states could cost up to £41 billion, although including all associated costs the Campaign for Nuclear Disarmament puts the nuclear upgrade at £205 billion. ICAN research released May 2020 showed that the United Kingdom spent $8.9 billion to maintain and modernize its nuclear weapons in 2019 alone. The UK leases its nuclear-capable missiles from the United States and its nuclear warheads are very similar to the U.S. W-76 warheads placed on the same missile.

UK Public Opinion on Nuclear Weapons

More than 60 members of the House of Commons, along with dozens of members of the Scottish parliament and the Welsh assembly, have pledged to work for the United Kingdom’s signature and ratification of the Treaty on the Prohibition of Nuclear Weapons. Many cities across the country, including Manchester, Brighton, Oxford, and Edinburgh, have also called on the government to join the treaty. In July 2020, the first minister of Scotland, Nicola Sturgeon, wrote that “the Scottish government is firmly opposed to the possession, threat, and use of nuclear weapons” and “I have called on the UK government to sign and ratify the treaty”.

A public opinion poll conducted in January 2021 by Survation on behalf of the Campaign for Nuclear Disarmament (CND) found that 59 per cent of Britons believe that their country should join the treaty, with just 19 per cent opposed to joining.

Nuclear Non-Proliferation Treaty

The 1968 Nuclear Non-Proliferation Treaty has 191 states-parties, and at its core, prohibits most of the world’s countries from acquiring nuclear weapons and commits five nuclear-armed states, including the United Kingdom, to pursue disarmament negotiations (Article VI).

Every five years, NPT states-parties meet to review progress on commitments and to adopt a consensus final document with additional commitments for treaty implementation. Past Review Conference documents in 2000 and 2010 have been sparsely implemented.

The 2020 NPT Review Conference has been postponed. At this conference, the five nuclear-armed states party to the treaty, including the United Kingdom, will answer to many non-nuclear-weapon states who argue they have not fully implemented the treaty, more than 75 years after its adoption.

Treaty on the Prohibition of Nuclear Weapons

The 2017 Treaty on the Prohibition of Nuclear Weapons, which currently has 86 signatories and 54 states parties, includes prohibitions of the use, testing, production and stockpiling of nuclear weapons, as well as positive obligations for states parties to provide assistance to victims of nuclear use and testing and environmental remediation for land contaminated by nuclear use and testing. It entered into force on 22 January 2021.

The treaty articulates two pathways for nuclear-armed states to join (Article 4). A nuclear-armed state may either join the treaty and the negotiate a time-bound plan for complete nuclear disarmament, or it may complete nuclear disarmament first and then join the treaty and cooperate with the designated international authorities to verify the “irreversible elimination of its nuclear-weapon programme.”

The United Kingdom has not yet joined the TPNW. States-parties to the treaty will meet late this year or early next year to advance the treaty’s implementation and universalization.

Available for Interview

Beatrice Fihn, Executive Director of the International Campaign to Abolish Nuclear Weapons, [email protected], (GENEVA)


Alicia Sanders-Zakre, ICAN Policy and Research Coordinator, [email protected](GENEVA)

About ICAN

The International Campaign to Abolish Nuclear Weapons (ICAN) is a global campaign working to mobilize people in all countries to inspire, persuade and pressure their governments to sign and ratify the Treaty on the Prohibition of Nuclear Weapons. ICAN is comprised of more than 600 partner organisations in over 100 countries and was awarded the 2017 Nobel Peace Prize.