Rebuilding the ladder: Options for boosting Britain’s nuclear posture

Executive summary

Context:

• The United Kingdom (UK) is faced with a new nuclear age, which raises questions as to the continued suitability of its nuclear posture. The ‘minimal, credible’ deterrent of a single nuclear-powered ballistic missile submarine (SSBN) on patrol, providing a Continuous At-Sea Deterrent (CASD), was designed for the post-Cold War order of the 1990s and 2000s. This world no longer exists. 
• Compared to previous decades, a series of factors are combining to raise questions about the future credibility of the UK’s current nuclear posture, including:
  • The United States’ (US) reprioritisation of its military posture to the Western Hemisphere and the Indo-Pacific, including a likely drawdown of forces in Europe;
  • Russia’s emboldened aggression – including greater risk tolerance – and renewed Russian interest in novel nuclear delivery systems; and
  • The rise of the People’s Republic of China (PRC) as a significant military power, which is investing heavily in its nuclear forces to modernise and expand its arsenal.
    
• Britain has to consider circumstances in which it may be faced by rapid escalation in Europe, with the potential for a multi-front crisis. It has to ensure that adversaries do not come to believe they possess significant leeway to conduct direct acts of aggression against the UK and its allies – even including limited nuclear use – while staying below the threshold for a British strategic nuclear response.

Questions this Report addresses:

• How have the nuclear postures of adversaries evolved?
• How did extended deterrence in the North Atlantic Treaty Organisation (NATO) evolve, and to what extent will the current posture remain suitable?

• Have recent attempts by the UK and France to bolster their nuclear postures gone far enough?

• What further steps can His Majesty’s (HM) Government take to strengthen Britain’s nuclear posture?

Key findings:

• Of the ‘CRINK’ countries – the PRC, Russia, Iran, and North Korea – three are nuclear powers, and Iran, despite American and Israeli air strikes, still appears to have the vestiges of a nuclear programme underway. Of this grouping, Russia is the most acute threat to the UK; it retains an extensive sub-strategic nuclear arsenal.
• Fears of the US abandoning security commitments to NATO are exaggerated. The rhetoric of American leadership aside, Washington has said and done nothing to indicate that it will revoke extended nuclear deterrence in the Euro-Atlantic. However, as a reduced US military presence in Europe could coincide with a multi-front crisis, the risk of Russia testing the credibility of this extended deterrence has increased.
• European NATO has neither the time, nor the spread and depth, of nuclear weapons expertise and capacity to debate and implement a radically different ‘European nuclear umbrella’. It would be unwise to rehash historical debates about other formats. The current format, including sub-strategic nuclear weapons sharing arrangements, is adequate. However, there should be a greater European effort to take the lead more within this framework.
• European NATO allies are aware of the growing nuclear deterrence gap, and have been in close consultation with Britain and France. To their credit, by committing to joining NATO’s Dual-Capable Aircraft (DCA) effort and exploring the concept of ‘forward deterrence’ (as well as enhancing their own bilateral cooperation) respectively, London and Paris have made steps to assuage them, but these efforts do not currently go far enough.
• The UK is missing a ‘rung’ on the ‘escalatory ladder’, as it does not possess a dedicated and sovereign sub-strategic nuclear weapon. Alternatives such as Trident in a sub-strategic role or conventional deep precision strike weapons cannot act as substitutes for the deterrent role of a dedicated sub-strategic nuclear weapon. While efforts to bolster Britain’s nuclear posture should be balanced with the dire needs for investment in conventional forces and the limits of the capacity of the Atomic Weapons Establishment (AWE), a sovereign sub-strategic nuclear weapon is needed.

Recommendations:

In order to boost the UK’s nuclear posture, HM Government should:

1. Deepen British-French nuclear coordination: The UK and France have made great strides in deepening their nuclear relationship. Next steps should aim to support Britain’s efforts to rebuild institutional muscle memory, and complicate Russian decision-making. This should include more direct participation in the French nuclear ‘Poker exercises’, potentially including one conducted outside of France.
2. Update public-facing nuclear doctrine: Public-facing UK nuclear doctrine has remained mostly unchanged over the last three decades. A refresh of the wording will complicate Russian decision-making.
3. Refresh defence nuclear education: Nuclear education across the British defence landscape is too siloed. Further efforts to spread nuclear knowledge across stakeholders would be useful.
4. Embrace DCA participation: A single double-hatted squadron is not an ideal contribution to nuclear sharing. A further two squadrons of F-35A Lightning II Joint Combat Aircraft should be procured, and faster. In addition to the benefits of a second nuclear power joining the DCA effort, embracing participation will help to rebuild institutional muscle memory should the UK decide to acquire sovereign sub-strategic nuclear weapons. 
5. Rekindle national nuclear consciousness: Greater efforts by HM Government to increase public awareness of the importance and cost-effectiveness of nuclear weapons for deterrence purposes should be pursued.
6. Develop a sovereign sub-strategic nuclear capability: Britain should develop its own air-launched sub-strategic nuclear weapon to help share the burden of the DCA effort and hedge against the risk that the Kremlin would calculate that Washington and/or Paris would hold back in extremis if facing Russian nuclear escalation. While there are a number of fiscal and timescale challenges, many of these could (and should) be mitigated. Avoiding gold-plated requirements and seeking imaginative cost-sharing mechanisms with allies could help to manage the burden.