Walk into one of the pubs frequented by British civil servants nowadays and mention the name ‘Sir Michael Quinlan’. You will likely be met with some puzzled looks, and perhaps a knowing nod – a disservice to a name that once commanded unanimous respect in Whitehall, and was held in high esteem across Europe and on both sides of the Atlantic. A formidable civil servant, Quinlan’s career spanned almost the entirety of the Cold War, most of which he served as Britain’s foremost in-house thinker on nuclear strategy, first as secretary to two Chiefs of the Air Staff, before rounding out his career as Permanent Secretary in the Ministry of Defence. He remained active in public life until his untimely death in 2009, penning detailed works on deterrence theory and the just war tradition, and vocally opposing the Iraq War.

Quinlan’s memory has since faded, as have many of the lessons he worked hard to instil in the post-war, post-imperial British establishment. Yet the significance of his work endures, and is of growing importance, both for Britain and her European allies. International competition between nuclear-armed powers is ramping up, while talk of a ‘second’ Cold War – however imprecise – is now commonplace. Indeed, Russia is modernising and expanding its nuclear arsenal at scale, including new weapons designs, forcing NATO to reconsider its posture in Europe.

China’s approach is even more significant, with Beijing engaged in the most extensive buildup of nuclear and conventional arms since the end of the Cold War: a revolutionary development that is already altering the nuclear strategic balance, with repercussions well beyond the Indo-Pacific. The footprint of North Korean influence is also growing steadily, and extends well beyond approximately ten thousand DPRK troops serving with Russian forces in Ukraine. A burgeoning industrial partnership with the Russian Federation is designed to increase the lethality of the DPRK’s nuclear arsenal and provide additional technological assistance, with Kim Jong-Un recently releasing details of the country’s first nuclear-powered submarine.

In addition to all this, India and Pakistan came to blows again in 2025, which, despite lowered levels of overt nuclear signalling, raised fresh fears of nuclear confrontation. Meanwhile, Iran retains robust ballistic missile capabilities and is still actively pursuing nuclear weapons, despite heavy setbacks in 2025 from Israel’s Operation Rising Lion.

These broader developments have influenced the policy of Britain’s allies, chiefly the United States, which is already scaling back its commitments to the European theatre, pivoting sharply to the Western Hemisphere, and doubling down on the defence of the Indo-Pacific. This move predates – and will outlast – the second Trump Administration. Indeed, this realignment must be seen as distinct from both the post-Cold War era and the Cold War itself, when a strong US nuclear guarantee underwrote NATO doctrine in Europe. In many respects it is redolent of the early Cold War, when Britain was without its own atomic arsenal, and entirely reliant on the US nuclear guarantee against Soviet invasion – a guarantee which was not always ironclad.

Today, this shift in US strategic priorities poses foundational questions for the deterrence doctrine of both Britain and her European allies, questions not asked in more than a generation. If he were alive today, what would Michael Quinlan think of this? Since the end of the Cold War, Britain and Europe’s intellectual capacity for thinking about nuclear weapons has eroded, creating gaps that are being exploited by their adversaries. Quinlan’s writings present key lessons, many of which are directly relevant to both British and wider European security today. Quinlan’s deterrence theory differs from the more rationalistic work of his contemporaries, particularly US scholars such as Herman Kahn, as his efforts were focused on Britain, a second-order world power carving a role for itself between the leviathans of the US and the USSR. As Britain could not match the industrial or economic might of either superpower in the atomic age, she sought to leverage her position to preserve the European balance of power, while defending her core national interests. As a result, Quinlan developed a theory that was robust, pragmatic, and disarmingly simple, and which would guide British and wider allied strategic thinking well after the end of the Cold War.

Quinlan’s thought was rooted in ethical and practical concerns, conditioned by a strong sense of pragmatism. For him, thinking seriously about nuclear questions was an inescapable moral activity of the very highest order, and the problems these weapons pose for European security are simply too momentous to avoid. This begins by acknowledging that nuclear weapons exist, and that they cannot be un-invented. To his mind, the notion that nuclear weapons can be eradicated is laudable yet naïve, and fails to treat the problem with the moral seriousness it deserves.

Despite this firm stance on nuclear abolitionism, Quinlan was far from hawkish in his outlook. An unremitting advocate of arms control treaties, he supported any activity that would limit the number of nuclear weapons in existence, or any diplomatic initiative that would actually reduce the likelihood of conflict, so long as this did not undermine the logic of deterrence. While the invention of nuclear arms made all wars between major powers an absurdity, the fact remains that they exist. In such a world, it is conventional wars that form the surest route to a full-scale nuclear exchange. Therefore, it has been morally incumbent upon states since 1945 to deter conflicts of all scales and sizes, both ‘conventional’ and ‘nuclear’, as far as possible.

For this reason, Quinlan thought that deterrence should be thought of not as a ‘ladder’, nor a ‘stack of sealed boxes’, but as a ‘package’, whereby the ‘various levels of military force are… complementary and interdependent; all… contribute to deterrence’. One either deters an adversary successfully, or they do not. This rests on a spectrum of capabilities, from ‘highest’ (strategic nuclear weapons) to ‘lowest’ (conventional small arms), including unconventional capabilities, such as covert or sub-threshold operations: capabilities which Britain routinely relied upon to project asymmetric power throughout the Cold War. Doing so leaves no significant gaps in either the political or military ability to manoeuvre between them with agility.

British and European deterrence rests, therefore, on its credibility: there is no point in procuring a nuclear arsenal if you do not intend, in extremis, to use it. A nuclear-armed, aggressive, totalitarian state, such as the Soviet Union, may pose an existential threat to Britain and her allies. Against such a threat, nuclear possession and even use are justified. Unilateral disarmament by responsible powers such as Britain or France would only worsen the security environment, leaving nuclear weapons in the hands of the most irresponsible or malign actors.

In this context, there is a strong ‘cognitive’ element to deterrence. It begins in the mind, both of yourself and of your adversary. An adversary must come to believe, through your possession of credible capabilities, posture, and communicated intent, that a full nuclear exchange could result from their actions. As such, there can be no clean separation of conventional and nuclear arms within deterrence doctrine. Separating one from the other, as Britain, France, and to a lesser extent the United States have done since the late 1990s and 2000s exposes gaps within the deterrence architecture, vulnerabilities which can be coercively exploited by an adversary. Such exposure may, counterintuitively, make nuclear confrontation more likely, as it encourages strategic risk-taking.

There is no clearer example of this doctrine than contemporary Russian strategic thought, which has in many respects accepted the core tenets of Quinlan’s work. Since the publication of its Military Doctrine document in 2010, Russia has explicitly embraced a ‘sliding scale’ of deterrence, lowering thresholds for nuclear use to exploit its preponderance of sub-strategic and tactical nuclear weapons. This is a clear recognition by Russian doctrinal thinkers of the validity of Quinlan’s viewpoint – a viewpoint widely held by British strategists during the Cold War, and by US strategists well into the 2000s. Recovering and reapplying this conceptual approach, while addressing capability gaps within British and allied European deterrence posture, would help minimise a potential adversary’s recourse to this form of exploitation, and provide options to counter such threats.

Yet the mere possession of such capabilities is necessary but not sufficient – it must be accompanied by the demonstrable ability and will to use them. This is combined with a degree of strategic ambiguity over the costs one is prepared to impose on an adversary. To this end, one must establish clearly in the mind of an adversary the damage they would suffer, and the political determination to impose such a cost, should certain national interests be threatened. This does not need to be symmetrical. Indeed, a core element of historic British deterrence doctrine is asymmetric, based on merely complicating Moscow’s decision-making, hence her role as the ‘second centre of decision’ within the NATO nuclear alliance. Since the start of the Cold War, it has been clear that Britain and France would never achieve parity of nuclear arms with Russia or the US. Nor do they need to. The role of the British nuclear arsenal was never to outgun the Soviet Union, but to provide a credible, independent force which threatens core Russian power centres. By introducing a second, independent layer of risk into Moscow’s decision-making, Britain could ensure that if the US nuclear guarantee ever wavered in a crisis, Russia would still be forced to consider Britain’s position before it acted.

British and European deterrence theory, like that of Michael Quinlan, was crafted in a bipolar world. Yet with the fall of the Berlin Wall and the collapse of the Soviet Union, these assumptions were revisited. Throughout the years of the ‘peace dividend’, when Yugoslavia collapsed in on its own Balkan contradictions and ‘global terrorism’ became a reality for the West, attention turned to rogue states such as Iran, whose support for non-state armed groups presented a new form of nuclear threat. In this unipolar atmosphere, Quinlan revised his own assumptions, too, and doubled down on certain aspects of his theory. Given the collapse of major state-based threats, he called on Britain to avoid wars of intervention, advocated for greater arms control regimes, and the limiting of nuclear stockpiles, to avoid the risk of nuclear confrontation.

However, the political conditions that upheld the post-Cold War order have steadily eroded, making this revised doctrine increasingly untenable, both for the UK and the continental European powers. Faced with a more uncertain world, how would ‘Quinlanism’ adapt today? First, Quinlan would re-emphasise Britain’s role as the ‘second centre of decision’ within NATO. Britain’s independent nuclear deterrent still provides additional complicating factors for Russia and other adversarial powers attempting to coerce or undermine her national interests. However, the conceptual underpinnings of its nuclear arsenal have been woefully neglected, leading Moscow to largely discount the British and French arsenals since the late-2000s. Strengthening this ‘second centre’ role to balance against greater US drawdowns in Europe, the rise of China, and Russian expansionism is a core priority for British and European deterrence. This begins with the ‘intellectual rearmament’ of European statesmen and officials, but it must be followed with capabilities to match.

Furthermore, Russian aggression and the challenge of China pose fundamental questions for NATO, and in particular the United States. Given the latter’s pivot to the Pacific, Quinlan would urge a far greater focus on Anglo-European cooperation, particularly with France. The 2025 Anglo-French Northwood Declaration on nuclear cooperation may provide a good forum for exploring a new language of European nuclear communication, over and above internal discussions in Whitehall. In spite of the obstacles it will face, Northwood represents the kind of nuclear alliance that Quinlan once advocated for, and is a positive step toward reintroducing these European arsenals into Russian strategic calculations.

The shortfalls in the potency of Britain’s nuclear arsenal have not gone entirely unnoticed in Whitehall. In 2025, the UK government purchased a small fleet of twelve F-35A strike fighters – the only F-35 variant capable of carrying US B61 nuclear gravity bombs – and announced its intention to rejoin the NATO nuclear sharing mission. This statement, broadly welcomed by the White House and NATO partners, is far from unprecedented: Britain maintained its own stockpile of sub-strategic and tactical systems for airborne deployment throughout the Cold War, only retiring them in 1998. At one level, then, the decision makes clear sense. Beyond being the preferred jet of choice for the RAF – as they are cheaper than the F-35B, with a better range and larger weapons payload – these aircraft will allow Britain to re-learn the processes necessary for maintaining an airborne sub-strategic nuclear capability: a vital step if it were to revive a credible sovereign system in the future.

However, procuring a US-made system provides Britain with no meaningful strategic autonomy. Unlike its Trident-armed submarines, which are operationally independent, this airborne fleet will be dependent on the US and unusable without its consent. Quinlan would, at best, regard the purchase as a preparatory exercise for reviving processes and relearning practices – a necessary step, but not sufficient for European deterrence. At worst, it can be read as a political decision that lacks strong military reasoning or broader theoretical foundations.

British targeting doctrine and nuclear readiness must also be re-examined. During the Cold War a British nuclear-armed submarine was capable of launching within fifteen minutes of an order being received, and its weapons were targeted in accordance with pre-existing doctrinal requirements. After 1998, this high-readiness state was substantially reduced, and although one nuclear-armed boat may always be at sea, the period for notice has moved from minutes to days; British missiles have been de-targeted, and are no longer programmed according to pre-arranged solutions. In a more volatile security environment, one in which Europe may even lack the full support of the United States, Quinlan would suggest revisiting these arrangements, updating Britain’s declared targeting policy and readiness, and relearning nuclear signalling and communication, ideally in tandem with France. This is a skill that many European capitals have simply forgotten, yet one which Russia, however haphazardly, is honing in Ukraine. Given the sharp disparity between their arsenals, London and Paris cannot afford to give Moscow the upper hand in signalling, too.

Quinlan conceptualised deterrence in distinctly British terms, yet today his work has broader relevance. Amid the threat from Russia, the challenge of China, and an overstretched United States, Quinlan’s thought can help revive European deterrence theory in the third nuclear age. While the threat from non-state actors remains, states have become the primary concern in this era of great power competition. Britain and her core European allies must keep pace with the technological and political developments of her peer adversaries and adjust her posture accordingly, whatever this may require: newer weapons, larger stockpiles, renewed arms control efforts. Crucially, it requires a return to the deep intellectual approach that once characterised British, and European, deterrence doctrine. In this we could do far worse than Sir Michael Quinlan. Rethinking these questions is essential, not only for London, but for a broader array of allies from Paris to Berlin, Ottawa to Canberra. Quinlan insisted that deterrence is simple. It involves imposing credible, unacceptable costs on an adversary, clearly communicated in terms they understand. Yet, in war, even the simplest thing is difficult.