Tighter Lips and Looser Controls: UK Nuclear Posture in the 2020s

The recent Integrated Review caught headlines for reversing cuts to the UK’s stock of nuclear warheads. Paul Rogers argues that we should be more concerned about the expansion of potential options for their use and the growing opacity of nuclear decision-making.


On 16 March this year, the Johnson government announced three changes to the UK’s nuclear posture: it would increase the upper limit on its stockpile of warheads by 44% to 280, reduce transparency about the make-up of the arsenal, and extend the circumstances in which the UK’s nuclear weapons might be used. There has been considerable debate and controversy over the expansion decision; this note concentrates more on the other two factors, transparency and potential nuclear use.

The Nuclear stockpile

The increase in the stockpile was described by leading US nuclear analyst Daryll G. Kimball as “a major reversal that will complicate efforts to strengthen the nuclear Non-proliferation Treaty and exacerbate tensions with other nuclear-armed states”. It also contrasted with the stated positions of Labour and Conservative-led governments from 1997 to 2015 which each reduced warhead numbers, leading to a planned total of 180 warheads, with 120 operationally available, by the mid-2020s.

In practice, the size of the UK’s nuclear warhead stockpile is monitored by the Nukewatch group, primarily by checking warhead movements which are all undertaken by road, over 700 km between the Atomic Weapons Establishment in Berkshire and the nuclear submarine base on the Clyde. It has reported that the increase in numbers had already started under the 2015-19 Conservative governments, so the expansion decision may actually have been made years ago without it being made public, perhaps an early indication of its new reluctance to engage in transparency on nuclear issues.


Whatever the reality on stockpile size, the government’s decision to end a period of relative transparency on the make-up and purpose of UK nuclear forces is a lot more worrying, especially when compared to the attitudes of the Blair, Brown and Cameron governments through to 2015. Then, reasonably clear indications of warhead power, composition and missile submarine loadings were in the public domain with the exception of the vexed question of what was variably called “tactical” or “sub-strategic” Trident.

This related to the withdrawal in 1998 of the UK’s last tactical nuclear weapon, the WE-177 air-dropped bomb which also existed in an anti-submarine naval variant. This “gap” was filled by a low-yield version of the standard Trident warhead and enabled the UK to have a range of options in the event of a nuclear war that fell far short of a full-scale nuclear conflagration.

As Trident was being developed in the 1990s, the authoritative military journal the International Defence Review published an assessment of how the UK might fight a limited nuclear war:

 “At what might be called the “upper end” of the usage spectrum, they could be used in a conflict involving large-scale forces (including British ground and air forces), such as the 1990-91 Gulf War, to reply to an enemy nuclear strike. Secondly, they could be used in a similar setting, but to reply to enemy use of weapons of mass destruction, such as bacteriological or chemical weapons, for which the British possess no like-for-like retaliatory capability. Thirdly, they could be used in a demonstrative role: i.e. aimed at a non-critical uninhabited area, with the message that if the country concerned continued on its present course of action, nuclear weapons would be aimed at a high-priority target. Finally, there is the punitive role, where a country has committed an act, despite specific warnings that to do so would incur a nuclear strike.”

David Miller, “Britain Ponders Single Warhead Option”, International Defence Review, September 1994.

Three of these four options implied use against a non-nuclear opponent and there was persistent if low-key controversy in the early years of the Trident deployment over the UK even considering such a nuclear posture. There is, indeed, anecdotal evidence that in the early 2000s the then Labour government ceased deploying the low-yield version, but it is not clear whether the incoming Conservative-led coalition (2010-15) persisted with this stance. What is clear now, is that in the new era of zero transparency, any debate on UK nuclear warfighting will be hugely limited by secrecy.

What we know from March’s Integrated Review report (pp.76-78) is that the UK not only reserves the right to use nuclear weapons in response to chemical and biological weapons but against “emerging technologies that could have a comparable impact”, presumably meaning cyber or similar assaults. It may also consider nuclear use against states aiming to acquire nuclear weapons – in the words of the Integrated Review, states considered “in material breach of [their] non-proliferation obligations”.

This is a bit rich for a state that has just announced an increase in its own nuclear stockpile, thus failing in one of its obligations to the Nuclear Non-Proliferation Treaty. It most likely refers to Iran, where the British government has made clear that Tehran must not be allowed to develop nuclear weapons.

The UK and nuclear warfighting[i]

What is clear is that the current government has expanded the circumstances in which small-scale nuclear use might be considered, in contradiction to the common view that such use would only be in response to an all-out nuclear attack on the UK – deterrence through the threat of mutually assured destruction (MAD).

There is a long history to this posture. Back in the mid-fifties when the UK was developing and testing early atom bombs, there was still a widespread belief in the country that it was one of the world’s three great powers along with the United States and the Soviet Union. Then, from the late 1950s and long before the submarine-launched Polaris or Trident missiles came on the scene, the UK had medium-range nuclear-capable bombers such as the Canberra, Valiant and Vulcan that could be deployed with nuclear weapons in the Middle East (from Cyprus) or South East Asia (from Singapore). From the early 1960s, the Royal Navy’s five large aircraft carriers could also deploy with Scimitar and Buccaneer nuclear-armed strike aircraft right across the world.

Even before this, in 1955 the defence minister at the time, Harold Macmillan, could tell the House of Commons that:

“…the power of interdiction upon invading columns by nuclear weapons give a new aspect altogether to strategy, both in the Middle East and the Far East. It affords a breathing space, an interval, a short but perhaps vital opportunity for the assembly during the battle for air supremacy, of larger conventional forces than can normally be stationed in those areas.”

Harold Macmillan, 2nd March 1954.

The theme of fighting a small nuclear war was further expressed during the 1957 Defence Debate by the Defence Minister, Duncan Sandys:

“one must distinguish between major global war, involving a head-on clash between the great Powers, and minor conflicts which can be localised and which do not bring the great Powers into direct collision. Limited and localised acts of aggression, for example, by a satellite Communist State could, no doubt, be resisted with conventional arms, or, at worst, with tactical nuclear weapons, the use of which could be confined to the battle area.”  

Duncan Sandys, 16th April 1957.

Such a nuclear war-fighting stance was reasonably standard at the time and contrasted with the common public view that nuclear weapons were all about deterrence through mutual assured destruction, a flawed view that persists to this day and is in marked contrast to UK government threats and even deployments in times of limited war.

Thus, in the 1982 Falklands-Malvinas war tactical nuclear weapons were at different times during the conflict carried on two aircraft carriers, two anti-submarine frigates and two Royal Fleet Auxiliary support ships. There were also leaks to the campaigning Labour MP Tam Dalyell and others that a Polaris missile submarine was deployed within range of northern Argentina. While vigorously denied by the government, the sources included a well-informed Conservative backbencher, a senior naval officer and a retired senior civil servant.

In the run-up to the 1991 war with Iraq, a senior source in the Army stated that tactical nuclear weapons were available for use in response to Iraq using chemical weapons, and just before the 2003 war the then Minister of Defence, Geoff Hoon, said in a TV interview that he could envisage circumstances in which British nuclear weapons were used in response to chemical or biological weapons or even if there was strong evidence of an imminent attack. He later backtracked on that but not before the message had been sent.


What is therefore clear from these three nuclear elements in the Integrated Review is that the UK is moving towards a greater reliance on its nuclear forces as potential war-fighting systems but is doing so while closing up on the extent of transparency over its forces. This will make any serious public debate on the wisdom of such a move far less likely at a time when the government is determined to ensure that the UK must be seen as the nearest thing possible to being a great power given its relatively weak economic status.

The Integrated Review may have attracted controversy over the overall increase in the nuclear stockpile, but it is the ending of the limited degree of transparency and the move towards a greater consideration of nuclear warfighting that are the key issues.

[i] This section summarises UK policies and practice in limited nuclear warfighting through to the early 2000s. A more comprehensive account is available in my evidence submitted to and subsequently published by the Defence Select Committee back in January 2007: https://publications.parliament.uk/pa/cm200607/cmselect/cmdfence/225/225we17.htm

The views and opinions expressed in posts on the Rethinking Security blog are those of the authors and do not necessarily reflect the position of the network and its broader membership.

Photo Credit: Thomas McDonald. Vanguard-class nuclear missile submarine HMS Victorious departs HM Naval Base Clyde at Faslane, Jan 2005.

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