There has been a lot of chatter recently about a European nuclear deterrent. Ever since the Trump administration took office, many US allies have been struggling with the rapid reorientiation of American foreign policy and the reprioritising of military capabilities to the Pacific. This has been accompanied by a more activist, and in some cases actively hostile, attitude in Washington toward its allies.

One of the causes of this is the fact that since the early 1990s, many US allies – including Britain – have neglected their defence capabilities, leading on the one hand to an over-reliance on the United States and, on the other, American resentment at having to carry more than its fair share of the burden.

The change in tone from Washington has been, for many, both sobering and anxiety-inducing. Several US administrations have placed pressure on its European NATO allies to increase their defence spending. Some of the more strident American commentary on this has even suggested Washington might step away from its NATO commitments if Europe did not invest significantly more in its own defence. This has led several states, including Poland and some of the Baltics, to openly question the longevity of the US nuclear deterrent, resulting in some continental states questioning whether there might be a European alternative.

One figure has emerged at the forefront of these discussions. Since 2020, French President Emmanuel Macron has been signalling his intent to extend protection of France’s nuclear arsenal to European allies. Many of his predecessors have made similar pronouncements, though none have taken the next step of moving beyond rhetoric to concrete action. Macron’s ideas were given structure in 2025 by the Anglo-French Northwood Declaration. This agreement promised that there is now no threat to European security that would not prompt a joint response from the nuclear arsenals of both London and Paris.

Northwood has now been reinforced by both policy and structure modifications to the French deterrent. At the start of March 2026, Macron announced what has been hailed as a new vision for European deterrence, increasing the French warhead stockpile while making the size of the stockpile itself secret. Furthermore, under the new policy, termed ‘forward deterrence’, French nuclear-capable jets could be deployed to allied countries, and France will work with the United Kingdom, Germany and a group of select European nations – Poland, the Netherlands, Sweden, Belgium and Portugal – to develop this concept in practice, including shared nuclear exercises. A Franco-German partnership will underpin this new doctrine, with a steering group to explore options for closer deterrence cooperation.

Whether one reads the Northwood Declaration or the ‘forward deterrence’ policy as a radical shift in posture is open to debate. Macron’s speech was plainly designed to display French capabilities without any corresponding increase in defence expenditure or additional systems. This may also be said of French actions in the Middle East, including the recent deployment of the Charles de Gaulle aircraft carrier and its escorts. Equally, raising France’s nuclear warhead cap merely echoes the policy decision taken by the UK five years ago during its Integrated Review, when the government raised the number of UK warheads from 225 to 260 and committed to the AUKUS programme. These moves are clearly meant to be seen as a powerful political signal. France has maintained an avowed policy of independence from NATO nuclear-planning structures since 1966. Conversely, the United Kingdom has aligned its nuclear arsenal with that of the United States since the early 1960s. Northwood has the potential to challenge both these assumptions.

Northwood will not, and cannot, supplant US extended deterrence, whose preservation is the most effective and economical solution for European security – a point reiterated in a letter by nearly all living US ambassadors to NATO and Supreme Allied Commanders, and which the Trump administration confirms is US policy. It is clear, however, that Europe must do more in concert with the United States to deter adversaries. Discussions within NATO should be held to address concerns about America’s extended deterrent ‘umbrella’, but these should focus on long-term strategic shifts driven by America’s emerging requirement to deter both Russia and China simultaneously. First, this will involve developing and deepening European long-range precision strike and air and missile defence capabilities. Second, the United Kingdom and France must consider developing stronger sovereign nuclear capabilities.

A recent paper presented at the Munich Security Conference offers a good overview of the nuclear options Europe has and the challenges in attaining them. Several of its proposals may be sound, and echo those in other publications. This includes bringing France more closely into NATO nuclear-planning structures, placing British and French personnel on secondment to each other’s nuclear exercises, even coordinating SSBN deployments. Many of these now feature as part of Macron’s vision.

In addition, convincing France to accept at least observer status in the NATO Nuclear Planning bodies would be an important step, although Paris has spurned proffered membership for decades. Equally, France should join Britain and the US in the NATO nuclear strike plan, which it can do without impinging in the slightest on its national nuclear decision-making prerogatives. By definition, a force which is not included in a coordinated plan cannot credibly act as part of the Alliance’s overall deterrent.

While welcome, these types of ‘software’ solution do not meaningfully add to European hard-power nuclear capabilities. This will require actively strengthening British and French nuclear and strategic forces. In some quarters, the ‘hard power solution’ generating the most vibrant discussion is the so-called ‘Eurodeterrent’. There have been myriad suggestions proposed under the rubric of this term, but most are unworkable in practice. Neither London nor Paris will or should give up sovereign control of their warheads or create an additional centre of nuclear decision-making in NATO.

One of the most popular solutions advanced involves expanding and possibly extending the French deterrent. Recent announcements view this as the natural option for a more European nuclear arsenal. Indeed, in some quarters there is an irritating feeling that France may have been right all along – that maintaining Gaullist self-sufficiency and a sovereign nuclear deterrent was a course European states should have steered some decades ago.

On the face of it, this makes some sense. Unlike London, Paris’ nuclear arsenal is seen as more flexible, more capable, and entirely sovereign, not reliant on any other power for its capabilities. While the British deterrent has been assigned to NATO since the 1960s, British nuclear capabilities, which have been entirely sea-based since 1998, are often regarded as too limited, inflexible, and reliant on the United States.

These assumptions, which are prevalent in popular and even official opinion, might raise eyebrows for some with a longer view on transatlantic nuclear security. Declassified US documents, not widely known in either the policy or academic worlds, indicate that in 1969, a year after testing its first nuclear weapon and three years after dramatically withdrawing from the NATO command structure, France secretly sought US assistance for their nuclear ballistic missile programme. In 1971, to support US interests, President Nixon authorised a covert policy of ‘minimal assistance’ to France’s nuclear programme. Two years later, secret talks led to the US developing a secret programme of assistance to bolster French warhead capabilities. A related programme of assistance to support the development of French SLBMs was also initiated. Paris has never acknowledged the existence of the assistance. French files remain classified, and even the declassified US material only runs through to 1975.

Highlighting this often-overlooked fact is not intended to downplay the strengths of the French deterrent. It is crucial, however, to bear in mind when discussing the ‘independent’ nature of the French deterrent, especially when French sources have historically implied that the force de frappe, because it is ‘independent’, is more sovereign and ‘reliable’ than its British equivalent. US assistance to the French nuclear programme has been extensive, long-lasting, and designed explicitly to support both American and French strategic interests.

Another viable way to strengthen the Alliance’s nuclear deterrent involves reimagining and redeveloping the UK’s independent nuclear capability. There are many pathways for this, but most would involve the UK reviving a second nuclear leg to complement Trident: an air, sea or land-based system, either with the French or Americans. Both options have been explored in the past; today they have taken on new relevance.

On the former, however, one should exercise caution. Deepening the Northwood Declaration, through exercises and personnel exchanges is all well and good, but cooperating on nuclear hardware has inherent challenges. It has not succeeded in the past, in part due to the French sovereigntist mindset around defence procurement. This attitude is deeply ingrained, and has recently been demonstrated through political disagreements over the nature of the Franco-German FCAS programme, which is now on the verge of collapse.

The domestic politics of France complicates this further. With the rise of Rassemblement National under Marine Le Pen and Jordan Bardella, it is unclear whether Macron’s vision for European deterrence will survive past 2027. Bardella has stated that, if the party wins power next year, he will adopt a transactional approach, refusing to extend deterrence guarantees unless allies buy French defence equipment. This, coupled with France’s historical aloofness, can only deepen one’s scepticism over an extended French deterrent, or the viability of an Anglo-French nuclear capability.

If Anglo-French cooperation is not politically or technically desirable, could the United Kingdom work with the United States on an air- or sea-based regionally oriented delivery system, carrying, for British forces, a UK nuclear warhead? The fundamental question here is more political than technical: will European states feel that another British-operated Anglo-American system was sufficiently independent from Washington to be operationally independent.

While these concerns are understandable, they fail to note the longstanding operational independence of the British deterrent. The United Kingdom has worked closely with the US since 1958, and hand-in-glove since the 1962 Nassau Agreement. This enabled London to co-develop a fleet of Polaris-armed nuclear submarines (SSBNs) and later on the UK’s acquisition of Trident II missiles topped with sovereign Holbrook warheads, now carried by the Vanguard-class SSBNs. Today both nations are cooperating on the build of the newest generation British SSBN, the Dreadnought-class, and a new warhead, the Astraea, to arm them, while deepening their shared defence-industrial bases through the AUKUS agreement with Australia.

These arrangements work extremely well, both for London and Washington. The former can project nuclear power at a vastly reduced cost, while the latter has an ally so closely aligned that it can act both as force multiplier in the NATO context as well as an independent centre of decision-making within NATO, complicating the actions of its adversaries. London’s nuclear delivery system, while technically reliant on the US, is not operationally reliant on the decision-makers in Washington. There is no ‘kill switch’ for a Royal Navy nuclear submarine, and in a crisis its arsenal acts as a powerful means of deterring aggression even if Washington, for whatever reason, declines to act.

All of the above make London, rather than Paris, the natural place to double down on European nuclear capabilities and cooperation, reducing reliance on Washington without severing transatlantic ties. This could involve purchasing or co-developing a new UK nuclear warhead to place on a new dual-capable air-launched standoff cruise missile, or purchasing the forthcoming SLCM-N nuclear sea-launched cruise missile. Any of these would strengthen London’s nuclear capabilities and, in light of the bloated regional nuclear arsenal Vladimir Putin has deployed over the last decade, provide NATO and the British prime minister with an ability to deter the threats those weapons pose – thereby restoring the flexibility that NATO possessed throughout the whole of the Cold War. Those NATO countries already engaged in dual-capable aircraft support of NATO’s nuclear deterrent could benefit, in particular, from a standoff nuclear capable system, enhancing their F-35’s credibility into the next decade.

None of these proposals are revolutionary. In one sense, this is reassuring. On both sides of the Atlantic, our forebears were confronted with the same challenges and trade-offs that we now face today. If allies are willing to engage with a French solution, they must also weigh the benefits of expanding the British arsenal, and establish mechanisms to make this a reality.

Paris has outlined its vision for European nuclear security, and some of its proposals may be sensible. The UK should engage where there is mutual interest. However, London should be clear-eyed about the performative dimension to French nuclear statecraft underpinning recent announcements, and the lack of substantive changes they introduce. In response, London must also establish its own vision for the Alliance, one shorn of fashionable shibboleths around the British and French arsenals, and rooted in a long-term strategic goal – a vision alive to the problems inherent in both Anglo-French and Anglo-American cooperation, grounded in nuclear history, and rooted firmly in Britain’s national interest. On this, perhaps the most significant factor may not be the French, but London’s Trinity House Agreement with Germany, and the willingness of Berlin, unlike Paris, to spend some hard cash on strengthening European nuclear security.

Franklin C. Miller dealt extensively with nuclear policy and nuclear arms control issues during his 31-year US government career, which included senior positions in the Defense Department and on the National Security Council staff. He was directly in charge of US nuclear deterrence and targeting policy from 1985 to 2001 and chaired NATO’s senior nuclear policy committee from 1997 to 2001.

Daniel Skeffington is a Doctoral Fellow at the Centre for Statecraft and National Security in the Department of War Studies, King’s College, London, and Senior Fellow at Policy Exchange.