Deterrence and British strategy
Open Briefing | No. SDR-04.2024
This is the fourth in a series of Open Briefings to the Strategic Defence Review (SDR) from the Council on Geostrategy. Our aim is to analyse ten key questions facing the Defence Review Team, from the vantage point of how the United Kingdom’s (UK) adversaries and strategic competitors see us (an approach known as Opposing Forces, or ‘OPFOR’). We will avoid euphemisms and address the challenges head-on. After holding an expert seminar, we will formally submit the briefings at the end of September. Our contributions are deliberately candid – and we invite comment and challenge from all quarters. This fourth Open Briefing looks at Britain’s ability to deter opponents:
The ability to deter a rival from undertaking a course of action one finds undesirable has always been central to national strategy. Deterring hostile action is normally cheaper than intervening to punish an enemy or reverse aggression.
Deterrence takes two principal forms:
Maintaining the military capability and demonstrating the political willingness to use it to punish infraction or aggression;
Denying an opponent the ability to pursue their goals, such as seizing an ally’s territory, without imposing a cost which they deem too high to bear.
Deterrence takes two supplementary forms:
Direct deterrence, whereby a country takes measures and signals its willingness to respond if it comes under direct attack;
Extended deterrence, where a country takes measures and signals its commitment to defend its allies and partners should they come under attack.
Direct deterrence is simpler than extended deterrence. An enemy normally understands that attacking another country or its critical interests will solicit a direct and forceful response. But even then, poor signalling on the deterrer’s part, and/or miscalculation on the part of the aggressor, may lead to the breakdown in deterrence, with the most famous example being the Argentine decision to invade the Falkland Islands in 1982 – a consequence of Britain’s decision to withdraw military assets from the South Atlantic in 1981 and the Argentine misunderstanding that His Majesty’s (HM) Government lacked the capacity and motivation to recover the islands.
Extended deterrence is more complex because it is harder to signal that a nuclear-armed ally will come to the aid of a non-nuclear ally should it come under attack. This requires a sophisticated system of general deterrence involving numerous interlocking components, such as a treaty-based defence commitment, a potent military industrial base, nuclear forces with a guaranteed second strike capability, the forward deployment of conventional forces to extend a nuclear-armed ally’s nuclear forces over a vulnerable non-nuclear ally, and deny enemies access to its territory.
Since 1952, the UK has been a declared nuclear weapons state. HM Government states that the purpose of the British nuclear forces is to protect the country from the most extreme threats to national security, in particular nuclear coercion or attack.
From 1968, the Royal Navy has maintained a Continuous At Sea Deterrent (CASD). This has come in the form of four nuclear powered ballistic missile submarines (SSBN), the minimum necessary to ensure the availability of at least one at all times. Initially provided by the Resolution class submarines, British nuclear forces are now based on the Vanguard class SSBNs. These are due to be replaced by the Dreadnought class from the early 2030s. Presently, Britain has at least 40 operational nuclear warheads on its deployed SSBN – which would allow it to wreck any conceivable opponent. Maintaining CASD absorbs approximately 6% of the defence budget.
Besides deterring attacks on itself, Britain also declares its nuclear forces to the defence of the North Atlantic Treaty Organisation (NATO). This shields NATO allies from aggression which bolsters Britain’s national security and increases its influence within the alliance. But this declaration relies on credible signalling.
HM Government has signalled again and again its willingness to escalate to protect its treaty allies, both through prime ministerial intervention and in national strategic doctrine. More importantly, the UK has taken measures to extend its deterrent over its allies. During the Cold War, up to 55,000 troops were deployed permanently to West Germany alongside a tactical air force to deter a Soviet attack; today, HM Government maintains a far smaller number of persistently deployed forces along the eastern front of NATO, though not in every exposed ally. While contemporary Russia does not have the strength of the Soviet Union, it remains unclear whether exposed allies, such as Latvia and Lithuania, without a British (or American) contribution remain more vulnerable than those, such as Estonia and Poland, which host their forces.
But Britain’s nuclear posture is not without problems. In recent years, the UK’s CASD fleet has been facing serious strains. HMS Vanguard, the first of its class, was commissioned in 1993, while HMS Dreadnought, the first of the new class of SSBN, is not expected to enter service until after 2030. As they age, the Vanguard class need to spend longer periods undergoing maintenance, which has had a knock-on effect in requiring longer patrols due to limited maintenance infrastructure. This has also led to struggles to retain and recruit adequate numbers of personnel. For example, on average a United States (US) SSBN spends 77 days on patrol, while a Vanguard class SSBN recently came home from an almost 200 day patrol. The credibility of the British CASD could be jeopardised over the next few years if the strains worsen.
In addition, it is not clear whether the UK will retain the capability to protect CASD – vital to maintaining a credible deterrent. Due to a lack in availability of nuclear-powered attack submarines, frigates, and maritime patrol aircraft – a consequence of successive cuts and historically-low investment in defence – Britain is struggling to protect its SSBNs as they leave and enter their base in Faslane. Allied assets are often called upon to help provide this protection.
Unlike the other officially recognised nuclear powers, including Russia, the People’s Republic of China (PRC), the US and France, the UK no longer maintains a ‘tactical’ nuclear delivery system. This is a gap which an adversary in possession of such a system and sufficient risk appetite could attempt to exploit. A tactical delivery system provides additional rungs on the escalatory ladder before one gets to strategic nuclear release. Although Britain can deliver a tactical (i.e., lower yield) effect using its strategic delivery system, it may never do so because such a release may be misconstrued by a well-armed enemy for a strategic attack. Britain retired its complementary air-launched nuclear delivery system in 1998; since then, the gap between initial hostilities and strategic nuclear strike has reduced HM Government’s ability to deter aggressors. This scenario becomes more problematic if tactical nuclear weapons are employed against a UK ally rather than Britain itself.
Finally, it is unclear whether NATO allies see the current British nuclear deterrent as sufficient in scale or depth to provide for an adequate deterrence in the future, especially as Russia has grown more aggressive and unpredictable and other nefarious actors (such as Iran) are pursuing nuclear programmes. This concern may be compounded if the US continues to focus more on the Indo-Pacific, especially as the PRC expands and modernises its own nuclear arsenal, creating an additional nuclear challenge.
So long as Britain maintains a functional guaranteed second strike nuclear system, it seems unlikely that enemies will attack direct British interests. But the situation becomes more uncertain in relation to the UK’s NATO allies or any other allies or partners HM Government may seek to cover. Unless, HM Government provides sufficient resources and political drive to ensure the timely renewal of the British nuclear forces and, potentially, the regeneration of a tactical delivery system, the UK may be less prepared to deter future contingencies. This may result in a reduction in its ability to lead and align its allies and partners and, consequently, reduce its geopolitical influence.
Recommendations for the Defence Review Team:
Maintain a minimum, credible, nuclear deterrent; particularly as the number of hostile states grows in scale and intensity. Britain should invest in expanding the nuclear submarine support and construction infrastructure. This may not be completed in time to bring forward the first Dreadnought class SSBN’s service date, but it can help the later vessels (and will allow for SSN-AUKUS production to be increased). Investing now in improved support facilities will avoid the maintenance scheduling issues which have forced the Vanguard class SSBNs into prolonged patrols. This would also support SSN availability, allowing for more adequate independent protection of the Royal Navy’s SSBN fleet.
Regenerate a small but credible tactical nuclear arsenal. This would avoid the risk of an adversary taking advantage of the existing gap, especially should the US become less committed to NATO in the future. The UK could develop its own free-fall bomb (akin to the previous WE 177) small enough for internal carry within the F-35B Lightning II Joint Combat Aircraft or buy a small number of F35A Lightning II warplanes, which are designed to carry tactical nuclear weapons. In the longer term it could develop a nuclear capable cruise missile for either the SSN-AUKUS or the Tempest warplane.
Expand the depth and presence of British forces in other exposed allies to provide them with nuclear cover. Given that NATO allies such as Poland are modernising their own forces, this should not take the form of a ‘British Army of the Vistula’ or ‘British Army of the Emajogi’. Rather, British forces deployed to Estonia and Poland should be made more permanent and additional battlegroups should be deployed and integrated into the national defence forces of other exposed allies, particularly Latvia and Lithuania.
Enlarge the SSN, frigate and maritime patrol fleets. This will ensure that in addition to other important tasks for these assets, the UK is able to guard its SSBN fleet independently. Becoming over reliant on allies for such a key capability signals a lack of determination to Britain’s nuclear armed opponents.
Signal, clearly, decisively, and frequently, the UK’s willingness to fight for every inch of NATO territory; ministers should continue to make regular visits to the most exposed NATO allies to reiterate HM Government’s view that any attack on them will be met with a full and decisive military response.
James Rogers is the Co-founder and Director of Research at the Council on Geostrategy.
William Freer is a Research Fellow in National Security at the Council on Geostrategy, where he works on strategic advantage and maritime affairs.
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