Nuclear BREXIT? The Future of the UK´s Nuclear Force after Leaving the European Union

In September 2014, Scottish independence referendum failed to deliver expected results for the pro-independence camp when 55% of Scots voted against the secession from the United Kingdom. However, the Brexit vote has opened up the topic of Scotland’s independence again. With the idea of a new Scottish referendum, the question regarding the UK’s future of nuclear force emerges. Since the UK’s nuclear force is located exclusively on Scottish territory from where it operates thoroughly (The Faslane and Coulport Naval Bases), Scottish independence might as well undermine the UK’s nuclear posture with Scotland being in a strong opposition to nuclear weapons whatsoever.The Scotland’s first minister and the head of Scottish National Party Nicola Sturgeon has already called for another referendum to secede from the United Kingdom and said that leaving the European Union as well as single market is not what the majority of Scots want(62 percent of Scots voted to stay in the EU[i]). What implications could Brexit have for the United Kingdom’s nuclear posture? Could the UK be heading towards unilateral nuclear disarmament?

The UK’s nuclear capability and infrastructure

In comparison to other established nuclear powers under the Non-Proliferation Treaty (NPT), British nuclear arsenal is the smallest of all and relies on a single weapon sea-based system. The United Kingdom has been successful in reducing its nuclear arsenal from 500 warheads in the Cold War peak years of 1973-1981 to 215 nuclear warheads as of 2017, of which 120 are operational, deploying only 40 on each submarine.[ii]In line with the commitment to disarmament, the UK plans to reduce its nuclear stockpile to 180 warheads overall by the mid-2020’s. The United Kingdom currently maintains only one type of ballistic missile system for delivering nuclear warheads – Trident II (D5) submarine-launched ballistic missile (SLBM) developed in the last years of the Cold War that succeeded previous Polaris SLBM.[iii] UK’s Trident weapons system consists of three technical components: the platform, the missile and the warhead. The platform is represented by four Vanguard-class submarines designed and built in the UK – HMS VANGUARD (1994), HMS VICTORIOUS (1995), HMS VIGILANT (1998) and HMS VENGEANCE (2001), each being equipped with 16 independently-controlled missile tubes.[iv] The submarines are fueled by Rolls Royce PWR2 nuclear reactor and each of them is 150 meters long with roughly 16 000 tons in weight. Missile tubes house Trident II (D5) missiles, capable of carrying 12 warheads each. Therefore, one Vanguard-class submarine can carry up to 192 warheads. Based on the 2010 Strategic Defence and Security Review, the number of launch tubes has been reduced to 8 with a maximum of 40 warheads per each submarine in line with the UK’s commitment to nuclear disarmament.[v] Trident missile is of U.S. origin with a range from 6 500 to 12 000 kilometers and is equipped with multiple independently targetable reentry vehicle (MIRV) capable of hitting multiple targets at the same time. The third component, nuclear warhead, is of UK’s origin and has an explosive yield of 100 kilotons.[vi]

The submarine fleet is supported by industrial and manufacturing infrastructure. As mentioned at the beginning, the submarine basing infrastructure – the operating base of the Royal Navy HM Naval Base Clyde is located at Faslane, Scotland and houses UK’s Vanguard SSBN’s. UK’s stock of nuclear warheads is stored at Coulport storage facility at the Royal Naval Armaments Depot (RNAD) near Faslane. The maintenance of the submarines is provided by Royal Navy and civilian personnel at HM Naval Base Clyde while refueling and refitting is carried out in Devonport, Plymouth by Devonport Management Limited (DML).[vii] The manufacturing, testing and commissioning of nuclear-powered submarines is performed by BAE Systems at the building yard Barrow-in-Furness in Cumbria. The expertise in the field of nuclear weapons for the UK’s nuclear deterrent is provided by the Atomic Weapons Establishment at Aldermaston, Berkshire.[viii]


The strategy of „minimal deterrence“

The United Kingdom’s nuclear weapons policy can be best defined as one of a “minimum deterrence”. The UK is the only nuclear state under the NPT that has reduced its nuclear deterrent capability to a single nuclear weapon system, which provides the UK with a minimum amount of destructive power necessary for achieving its deterrent objectives – to deter nuclear blackmail and acts of aggression against the UK and its vital interests as well as against its NATO allies.[ix] The UK has adopted the concept of “minimal deterrence” after the Second World War and this idea has dominated government thinking until today. The UK considers essential for its security to maintain independent, assured and credible nuclear deterrent as long as it is necessary providing global security situation and the risk of nuclear, chemical or biological proliferation. Therefore, in order to protect the UK from a risk stemming from proliferation of weapons of mass destruction or from possible nuclear terrorism, the UK has maintained its right to minimal and continuous nuclear deterrent. Since 1969, the Continuous at Sea Deterrence (CASD) with only one submarine on active 24 hours and 365-day patrol (known as Operation Relentless) has provided the UK with security insurance policy.[x] In order to maintain the credibility of a nuclear deterrent, the UK has also decided to replace four Vanguard-class submarines, which are expected to leave service in 2030’s for the Dreadnought-class submarines or also called Successor submarines. Although high (one of the largest government investment programmes with a total estimated cost of around £31 billion), such investment is considered crucial for the security of the UK, including its NATO allies.[xi]


The use of nuclear weapons is subjected to only extreme situations of self-defence as well as the defence of NATO allies. Since 1994, UK’s missiles have not been targeted at any particular state. Britain also maintains declaratory constrains regarding how, when and at what scale would nuclear weapons be used or threatened to be used.[xii]The UK has committed not to use or threaten to use nuclear weapons against a Non-Nuclear Weapons State party under the NPT. However, this does not apply to the states breaching non-proliferation commitments by developing nuclear, chemical or biological weapons.In the UK, the only person who has the mandate to authorize the use of nuclear weapons is the Prime minister.[xiii]


Based on the Nassau Agreement, the UK has been contributing to NATO collective Euro-Atlantic security since 1962 by committing its nuclear capability to the defence of Alliance, which is one of the key components of NATO nuclear strategy.[xiv] As a part of the UK’s nuclear weapons policy, Britain has been cooperating with the United States (1958 Mutual Defence Agreement) in nuclear matters. The current Trident II (D5) missiles as well as previous Polaris missiles have been manufactured in the U.S. (1963Polaris Sales Agreement), what have saved Britain a lot of money. The British government stated that this “special relationship” with the U.S. regarding nuclear weapons is not disrupting the UK’s independence in operating its nuclear deterrent capability. What is more, this special relationship explains the special status of the UK in NATO nuclear strategy, being one of the two parties to be in control on the “launch key”, sharing it with the U.S. The UK has therefore assured itself the deterrent capability on two fronts. One under the NATO and one under its own minimal deterrent in case of a failure of collective NATO nuclear deterrence.[xv] The UK has also been working closely with France (2010 Teutates Treaty) on defence, security and technological matters regarding safety and effective exploitation of their respective nuclear stockpiles.[xvi]


Since the end of the Cold War, the UK has been investing a lot of effort in global nuclear disarmament and has taken many non-proliferation initiatives. However, according to the latest National Security Strategy and Strategic Defence and Security Review 2015, the UK plans to maintain its independent nuclear deterrent “for as long as the global security situation demands”.[xvii]


Nuclear Brexit?

The Brexit has made a new referendum on Scottish independence more likely and so the future of the United Kingdom’s nuclear force after leaving the EU has been called into question. Many argue that Scottish independence would eventually force the UK to surrender its nuclear capability. The rationale behind this assumption is twofold. Firstly, there is a strong and longtime opposition of British and Scottish citizens against the possession of nuclear weapons. What is more, the leading Scottish National Party that has been supporting Scottish independence since its establishment in 1934, synonymized independence with a complete eradication of nuclear weapons from Scottish territory.Adding to this fact, 58 out of 59 Scottish MP’s voted against the renewal of the current Trident nuclear program last year.[xviii]In case of voting “yes” to independence, it is likely that the Scottish government would therefore seek a speedy removal of nuclear weapons from its territory. Moreover,according to independence White Paper from 2013, Scotland would not allow for a long-term housing of UK’s nuclear forces. Secondly, since the UK’s nuclear force could not be housed on Scottish territory for a long time due to a strong opposition, the UK would have to find alternative facilities to house its nuclear force. However, there are many reasons (legality, geography, finance, functionality, public prestige) that would make the effective relocation of the UK’s nuclear force rather impossible. Not at least, relocating nuclear forces to another place would most likely sparkle huge protests in its vicinity as well as cost a lot of money.Stationing the UK’s nuclear forces overseas with its allies, mainly the U.S. and France, would undermine the UK’s independence in maintaining its nuclear deterrence. Not having a feasible domestic as well as foreign scenario, the UK would be left with the only option –unilateral nuclear disarmament.[xix]

Even though the United Kingdom is in favor of the idea of a complete nuclear disarmament, according to Defence and Security Review 2015, maintaining its independent nuclear deterrentis of vital importance due to a current global security environment and so the possible Scottish independence could greatly undermine the UK’s nuclear posture and subsequently its status as a nuclear power.

Written by Jana Bandurová


[i]EU referendum: Scotland backs Remain as UK votes Leave. BBC News [online]. 2016 [Accessed 2017-06-12]. Available at:

[ii]Norris, Robert S. a Hans M. Kristensen. The British nuclear stockpile, 1953–2013. Bulletin of the Atomic Scientists [online]. 2015, Vol. 69, No. 4, p. 70 [Accessed 2017-06-10]. DOI: 10.1177/0096340213493260. ISSN 0096-3402. Available at:

[iii]Freedman, Lawrence. “Britain: The First Ex-Nuclear Power?” International Security, vol. 6, no. 2, 1981, p. 80,

[iv]The Future of the United Kingdom’s Nuclear Deterrent: The Current System. GOV.UK: Fact Sheet 4 [online]. 2006 [Accessed 2017-06-10]. Available at:

[v]Securing Britain in an Age of Uncertainty: The Strategic Defence and Security Review. HM Government, 2010, p. 5 [online]. [Accessed 2017-06-10]. Available at:

[vi]The UK’s Strategic Nuclear Deterrent. Select Committee on Defence Eight Report [online]. [Accessed 2017-06-10]. Available at:

[vii]The future of the UK’s Strategic Nuclear Deterrent: The Manufacturing and Skills Base: Fourth Report of Session 2006-07 [online]. House of Commons, Defence Committee, 2006, p. 9. [Accessed 2017-06-10].

[viii]The UK’s Strategic Nuclear Deterrent. UK Parliament Website [online]. [Accessed 2017-06-10]. Available at:

[ix]The Future of the United Kingdom’s Deterrent. Ministry of Defence, 2006, p. 17. [online]. [Accessed 2017-06-10]. Available at:

[x]National Security Strategy and Strategic Defence and Security Review 2015: A Secure and Prosperous United Kingdom [online]. HM Government, 2015, p. 34 [Accessed 2017-06-10]. ISBN 9781474125963. Available at:

[xi]Ibid, p. 34

[xii]Securing Britain in an Age of Uncertainty: The Strategic Defence and Security Review. HM Government, 2010, p. 37 [online]. [Accessed 2017-06-10]. Available at:

[xiii]National Security Strategy and Strategic Defence and Security Review 2015: A Secure and Prosperous United Kingdom [online]. HM Government, 2015, p. 35 [Accessed 2017-06-10]. ISBN 9781474125963. Available at:

[xiv]NATO’s nuclear deterrence policy and forces [online]. North Atlantic Treaty Organization, 2015 [Accessed 2017-06-10]. Available at:

[xv]Yumin, Hu. British Nuclear Strategy with Its Own Distinct Features. Carnegie Endowment for International Peace [online]. China Arms Control and Disarmament Association, 2012 [Accessed 2017-06-10]. Available at:

[xvi]Kristensen, Hans M. a Robert S. NORRIS. British nuclear forces, 2011. Bulletin of the Atomic Scientists [online]. 2015, Vol. 67, No. 5, p. 93 [Accessed 2017-06-10]. DOI: 10.1177/0096340211421474. ISSN 0096-3402. Available at:

[xvii]National Security Strategy and Strategic Defence and Security Review 2015: A Secure and Prosperous United Kingdom [online]. HM Government, 2015, p. 34 [Accessed 2017-06-10]. ISBN 9781474125963. Available at:

[xviii]SNP push again for Scottish independence vote after Trident result. The Guardian [online]. 2016 [Accessed 2017-06-12]. Available at:

[xix]MacDonald, J. (2014) A blessing in disguise? Scottish independence and the end of the UK nuclear posture. European Security, Vol. 23, No.3, pp. 326-343.