Policy paper

2010 to 2015 government policy: UK nuclear deterrent

Updated 8 May 2015

This was published under the 2010 to 2015 Conservative and Liberal Democrat coalition government

This is a copy of a document that stated a policy of the 2010 to 2015 Conservative and Liberal Democrat coalition government. The previous URL of this page was https://www.gov.uk/government/policies/maintaining-an-effective-independent-nuclear-deterrent. Current policies can be found at the GOV.UK policies list.

Issue

The protection and defence of the UK is a primary responsibility of the government. The government is committed to maintaining the UK’s national nuclear deterrent, based on a ballistic missile submarine, for as long as the global security situation makes that necessary.

Actions

The purpose of our nuclear weapons is to deter an attack on the UK, our vital interests or our allies. The UK is committed to maintaining only the minimum deterrent necessary to achieve our deterrence objectives. They are viewed as political weapons, we would use nuclear weapons only in extreme circumstances of self-defence and would not use any of our weapons contrary to international law.

We have 5 principles that would inform any decision about the use of nuclear weapons.

The UK’s nuclear deterrent force consists of 4 Vanguard class ballistic missile submarines (SSBN). These can carry up to 16 Trident II D-5 ballistic missiles, which will reduce to 8 operational missiles per SSBN following decisions made in the 2010 Strategic Defence and Security Review (SDSR). At least one SSBN is constantly on patrol. This is known as ‘continuous at sea deterrence’ (CASD), and has the name Operation Relentless.

CASD is the most significant part of our deterrence activity. It provides a constant, credible and capable deterrent against nuclear blackmail and acts of aggression against the UK’s vital interests including our NATO allies. CASD is the UK’s most enduring current operation and has been successfully operating for over 40 years.

On 18 May 2011, the Ministry of Defence (MOD) announced that the first milestone (known as ‘initial gate’) had been passed in the programme to produce a successor to the Vanguard class submarines. The programme is now in a 5 year-long, £3 billion period of work known as the ‘assessment phase’.

The main purpose of the assessment phase is to refine the design of the successor submarine before we take the main investment decision (known as ‘main gate’), in 2016. At that stage we will also decide on the number of submarines needed to maintain our CASD. The first submarine is expected to enter service in 2028.

Background

UK nuclear deterrence policy is based on the white paper, The future of the UK’s nuclear deterrent December 2006, as amended by the Strategic Defence and Security Review, 2010.

The SDSR states that ‘we will retain and renew our nuclear deterrent, the United Kingdom’s ultimate insurance policy in an age of uncertainty… It is right that the United Kingdom should retain a credible continuous and effective minimum nuclear deterrent for as long as the global security situation makes that necessary.’

The UK’s security position has changed since the Cold War, and the threat has now changed, but the global context does not justify complete UK nuclear disarmament. In view of the continued existence of large nuclear arsenals, the possibility of further proliferation of nuclear weapons in combination with the risk of increased international instability and tension, we believe that a nuclear deterrent is likely to remain an important element of our national security in the 2020s and beyond.

Appendix 1: UK nuclear deterrence

This was a supporting detail page of the main policy document.

UK nuclear deterrence policy consists of 5 main principles:

• preventing attack - the UK’s nuclear weapons are not designed for military use during conflict but instead to deter and prevent nuclear blackmail and acts of aggression against our vital interests that cannot be countered by other means
• the UK will retain only the minimum amount of destructive power required to achieve our deterrence objectives - this is known as ‘minimum deterrence’
• we deliberately maintain some ambiguity about precisely when, how and at what scale we would contemplate use of our nuclear deterrent. We do not want to simplify the calculations of a potential aggressor by defining more precisely the circumstances in which we might consider the use of our nuclear capabilities (for example, we do not define what we consider to be our vital interests), hence, we will not rule in or out the first use of nuclear weapons
• the UK’s nuclear deterrent supports collective security through NATO for the Euro-Atlantic area
• an independent centre of nuclear decision-making enhances the overall deterrent effect of allied nuclear forces: separately controlled but mutually supporting nuclear forces create an enhanced overall deterrent effect; the UK deterrent is operationally independent, and the UK does not require US or NATO authorisation to use its deterrent - UK nuclear weapons remain under political control at all times; only the Prime Minister can authorise the firing of UK nuclear weapons

The UK has probably the smallest nuclear arsenal of the 5 states recognised as nuclear weapons states (NWS) under the Nuclear Non-Proliferation Treaty (NPT). We are the only NWS to rely on a single weapons system.

In 2010 we announced an update to our nuclear declaratory policy to ensure it is appropriate to the current political and security context. The UK has long been clear that we would only consider using nuclear weapons in extreme circumstances of self-defence, including the defence of our NATO Allies, and in accordance with our international legal obligations, including those relating to the conduct of armed conflict.

We are now able to give an assurance that the UK will not use or threaten to use nuclear weapons against non-nuclear weapon states parties to the NPT that are compliant with the NPT. This assurance would not apply to any state in material breach of those non-proliferation obligations.

While there is currently no direct threat to the UK or its vital interests from states developing capabilities in other weapons of mass destruction, for example chemical or biological, we reserve the right to review this assurance if the future threat, development and proliferation of these weapons make it necessary.

Appendix 2: successor deterrent programme

This was a supporting detail page of the main policy document.

In December 2006, the government published a white paper, which set out the conclusions of studies into whether the United Kingdom still required a nuclear deterrent and, if so, how that nuclear deterrent might best be provided.

The white paper concluded that, whilst at the time there was no nation with both the capability and intent to threaten the independence or integrity of the UK, we could not dismiss the possibility that a major direct nuclear threat to the UK might re-emerge despite our work to prevent the spread of nuclear weapons.

The white paper also concluded that, of the potential ways of providing a nuclear deterrent capability, the most effective system was a further class of submarines carrying ballistic missiles. In March 2007, Parliament voted to endorse the conclusions of the white paper.

Following this Parliamentary endorsement, the Ministry of Defence (MOD) began work to assess different options to determine how best to set up an affordable and credible ballistic missile submarine that met a demanding set of technical and operational requirements and which was capable of providing a credible deterrent capability well into the second half of this century.

This work culminated in the Successor ‘initial gate’ business case and the recommendation that the MOD develop a design based on a new nuclear propulsion system (known as Pressurised Water Reactor (PWR) 3) and a missile compartment that would be jointly developed with the United States. It was also recommended that the MOD proceed with a 5 year long, £3 billion assessment phase during which the design would be refined, preparations would be made for the build programme, and long lead items ordered.

In April 2011, the Chief Secretary to the Treasury approved the initial gate decision, and this was announced to Parliament in May 2011. The United Kingdom’s future nuclear deterrent: the submarine initial gate parliamentary report was published at the same time, explaining the initial gate decisions and setting out the MOD’s plans for the assessment phase.

The costs of the deterrent programme were explained in the 2006 white paper, these are :

• £11 to 14 billion for the submarine
• £2 to 3 billion for the warhead
• £2 to 3 billion for infrastructure

This totals £15 to 20 billion. All costs shown are at 2006/07 constant prices.

Current forecast costs, including planned efficiency measures indicate that we remain within the 2006 white paper estimates of £11 to14 billion (at 2006/07 prices) for the submarine costs.

The Strategic Defence and Security Review 2010 concluded that we could defer decisions on the warhead and infrastructure elements of the programme. Therefore, no further updates to these costs have been produced and the estimates given in the 2006 white paper of £2 to 3 billion for the warhead and £2 to 3 billion for the infrastructure are still valid.