Great Britain

Great Britain’s nuclear weapons program is called Trident and their nuclear arsenal consists of approximately 215 warheads.


Operation Hurricane

Britain began efforts to research the feasibility of developing a nuclear bomb in 1941 through the Tube Alloys project. The work continued in 1943 with participation of British scientists in the Manhattan Project in the United States. After the Second World War, Britain resumed its indigenous nuclear weapons programme and conducted its first nuclear test in October 1952, labelled Operation Hurricane. In 1958, the US and Britain resumed cooperation on nuclear weapons.

Early British nuclear weapons were gravitation bombs to be delivered by bomber aircraft. In 1968, the first generation of Resolution class submarines was introduced. These were equipped with Polaris long-range submarine-launched ballistic missiles (SLBMs) armed with nuclear warheads. Britain’s sea-based nuclear forces underwent modernization during the 1980s, with the introduction of American Trident missiles, as well as the introduction of new Vanguard-class submarines during the 1990s.

From 1952 to 1991, Britain conducted 88 nuclear tests, 64 of which were atmospheric. The first nine took place in Australia; subsequent nuclear tests were conducted at the island state of Kiribati in the Pacific Ocean and at the Nevada test site in the United States.

Nuclear weapons today

Britain currently maintains 225 nuclear warheads, of which 160 are deployed on its submarine fleet. This is roughly half the number of British nuclear weapons maintained in the 1970s. In 2010, Britain revealed plans for a further reduction in the number of operational warheads from 160 to “no more than” 120 warheads. This will result in cuts in the total number of nuclear warheads from 225 today down to “no more than 180 by the mid 2020s”.

Delivery systems


British SSNB

Britain maintains only one platform for delivery for nuclear weapons today—its fleet of four nuclear-powered Vanguard-class strategic submarines (SSBNs) operated by the British Royal Navy. Each submarine is equipped with 16 US Trident II ballistic missiles armed with about 48 nuclear warheads per submarine. Each nuclear warhead has a detonation yield of up to 100 kilotonnes of TNT, equivalent to about eight times the destructive yield of the atomic bomb the US exploded over Hiroshima in 1945.

Only one of the four British SSBNs is on active patrol at sea at any given time. Two of the three remaining SSBNs can be deployed on short notice, while the fourth SSBN is scheduled for repairs and maintenance and thus would require longer time for deployment. The patrolling SSBN is on a low readiness level and can only launch its missiles a few days after receiving launch orders according to the British government. The missiles onboard are not pre-programmed to strike fixed targets, and require target programming in accordance with the launch order, based on data provided by the US.

  • Trident II D5: The Trident II D5 is a three-stage, solid-fuelled submarine-launched ballistic missile (SLBM), developed by the US-based Lockheed Martin corporation. The US-built Trident II D5 missile is currently deployed on both US Ohio-class and British Vanguard-class SSBNs, with the Royal Navy operating the British Trident II D5 missiles through a lease agreement with the United States. The Trident II D5 has a range of more than 7,400 km, and is believed to carry either a single warhead or three multiple independently targetable re-entry vehicle (MIRV) warheads, each with a yield of up to 100 kt.

Trident SLBM

In addition to the British-operated Trident II D5 SLBMs, Britain also hosts 110 land-based US tactical nuclear weapons deployed at the Lakenheath military base as part of the nuclear sharing arrangement between the US and its NATO allies.

Nuclear weapon modernization

In 2007, the British parliament voted in favour of former British Prime Minister Tony Blair’s proposal to modernize Britain’s SSBN fleet. Without such a modernization, the British SSBNs would have faced obsolescence and withdrawal from service around 2024. Britain could thereby have become the first nuclear-weapon state to have abolished its nuclear weapons. Rather than going in the direction of comprehensive nuclear disarmament or postponing the modernization of its nuclear weapons for an indefinite time, Britain chose to modernize its nuclear arsenal. The decision was then taken with the goal of lengthening the service time of the Trident-missiles until 2055.

The details around Britain’s SSBN fleet modernization remain to be seen, and there will most likely also be a requirement that British missiles and their nuclear warheads are modernized in order to maintain a British nuclear capability. These decisions have been postponed until 2016, after the next parliamentary election. Financial costs are a strong concern. The current Trident missile system is believed to cost 1.8 billion pounds annually until 2024. Modernization of British SSBNs could cost an additional 15-20 billion pounds as a one-time cost, in addition to comparable annual costs for operation.

Fissile material inventory

Britain maintains a significantly smaller amount of fissile materials that could be used for nuclear weapons than the US and Russia. While Britain currently possesses the highest inventory of civilian separated plutonium in the world, only a small portion is declared as surplus for military requirements, with the remainder being placed under EURATOM safeguards at the Sellafield reprocessing plant, pending further IAEA safeguards. The same is true of Britain’s inventories of highly enriched uranium (HEU), which are relatively small compared to US and Russian levels.

The role of nuclear weapons in national security strategy

Britain’s national security strategy is explained in the Command Paper entitled “The Future of the United Kingdom’s Nuclear Deterrent”, which was presented to the British Parliament in 2006, as well as in the document Strategic Defence and Security Review” (SDSR), published in 2010. According to these documents, Britain maintains a nuclear force sufficient to deter “nuclear blackmail” (the ability to resist threats of nuclear use against Britain in crisis scenarios), as well as other threats to vital British interests. The SDSR does, however, assert a “negative security assurance”, stating that Britain will not use or threaten the use of nuclear weapons against non-nuclear-armed states that have joined the Non-Proliferation Treaty (NPT) and are in compliance with their treaty obligations.

The British government contends that the current international security climate does not warrant a total disarmament of British nuclear weapons, as long as other states retain nuclear weapons and there is a continuing risk of further nuclear proliferation to new states. Nuclear weapons are therefore presented as the only viable alternative for deterring future threats against Britain. The documents outlined above do, however, state that there is room for significant future reductions in the nuclear arsenal as compared to the levels maintained during the Cold War, without risking a deterioration of British security.


David Cameron and Barack Obama

The 2006 Command Paper further states that Britain will only consider the use of nuclear weapons for self-defence purposes (including the use of nuclear weapons to defend allied NATO-members), and even then only in extreme circumstances.



Last update: March 16, 2017