We are living through the most volatile period in world politics since the end of the Cold War. Russia’s aggressive, expansionist intentions in Europe, alongside the massive buildup of China’s nuclear capabilities, has brought deterrence between states and alliances back to the forefront of world politics. Yet despite the worsening international security environment and renewed great power competition, the UKs nuclear doctrine remains stuck in a post-Cold War mindset. Since 1989, Whitehall’s intellectual capacity for thinking about nuclear weapons has degraded substantially. Given heightened international instability, it is past time that London re-examines its deterrence doctrine, and its applicability to current circumstances.
A new paper for Policy Exchange co-authored by the former Chief of the Defence Staff Lord Stirrup KG GCB AFC and myself, argues that the UK Government has not seriously revised Britain’s nuclear deterrence doctrine since the end of the Cold War. We revisit the work of Sir Michael Quinlan, former Permanent Secretary at the MOD, and one of the great nuclear strategic thinkers of the Cold War. He developed an influential theory of nuclear deterrence with transatlantic influence, shaping allied doctrine at the height of NATO’s confrontation with the Soviet Union.
Do the challenges we face differ from those of the Cold War, and does a Cold War strategist have relevance today? While some have dubbed our contemporary, fragmented and multipolar world order as “Cold War II”, the geopolitics look significantly different to the bipolar confrontation between NATO and the Warsaw Pact. Since 1989, nuclear challenges of the post-Cold War era have been from rogue states like Iran or North Korea to terrorist actors acquiring dirty bombs. These have not disappeared, and great power competition has returned alongside these newer threats. China’s power has risen enormously in the past two decades, with a nuclear arsenal designed to challenge that of the United States. Russian doctrine has also shifted markedly, tolerating far lower thresholds for nuclear use, designed to coerce adversaries and support battlefield operations.
As a result, the U.S. is increasingly being drawn toward the Western Hemisphere and the Indo-Pacific to counter Russian and Chinese influence. Once a staunch supporter of European and NATO security, this pivot by America provides foundational challenges to European security, as the U.S. rebalances its commitments across multiple theatres. Given the serious and deteriorating international situation, the UK must rethink its place within a more uncertain, multipolar world, carving out a role within NATO nuclear planning whilst preserving its national interests. These are fundamentally underpinned by its nuclear deterrence doctrine.
Returning to thinkers such as Quinlan and applying them to our own era provides a roadmap for updating the purpose of Britain’s nuclear arsenal, which has suffered from conceptual uncertainty and a reduction of arms since 1989. After the end of the Cold War the UK reduced her nuclear capabilities to a minimum, retiring her last sovereign tactical nuclear weapons in 1998, and placing an even greater reliance on the Anglo-American nuclear alliance. London’s intended purchase of twelve nuclear-capable F-35A fighter jets, announced in 2025, promises to begin reversing this trend, returning the UK to the NATO nuclear sharing mission. This will allow the RAF to practise the processes, drills, and exercises which make for an effective tactical nuclear capability.
Yet this alone is not sufficient. Deterrence cannot be based simply on possessing nuclear capabilities, however potent they may be; it must be accompanied by a demonstrable ability, and will, to use them in extreme circumstances. To effectively deter its adversaries the UK should start relearning the practices and processes which enable this. In that vein, it should consider reviving large-scale Cold War-style military exercises with a nuclear component, in concert with allies and partners, perhaps along the lines of the WINTEX-CIMEX simulations from the 1980s.
Rearming ourselves in a nuclear capacity therefore begins here, in the mind
While F-35As will allow Britain to begin exercising with a nuclear component again, the UK, and particularly the UK government, lacks the strong intellectual resources it once possessed for thinking through these challenges. There is a strong “cognitive” element to deterrence: our adversaries must believe that a full nuclear exchange may result from their actions. If they do not believe this, then all the capabilities in the world will not stop them from testing our resolve.
Rearming ourselves in a nuclear capacity therefore begins here, in the mind. The great strategists of Sir Michael Quinlan’s generation knew this well. In a more multipolar nuclear world, we must grapple with this reality, bring their thoughts to the front of our minds, and deal with the challenges this presents us. Thinking seriously about nuclear weapons is an inescapable moral activity. Nuclear weapons exist, and they are not going anywhere any time soon. Given this stark reality, London’s primary aim must be to make all wars, of all scales, “unthinkable”. This begins with a doctrine for deterring conflict, preventing an adversary from coercing us in a way which would harm British national interests.
