10 Jul Enhanced Franco‑UK Nuclear Coordination to Counter Threats
Macron and Starmer agree on coordinated nuclear posture, RAF acquires 12 F‑35A jets with B61 capability, reinforcing deterrence against Russia.
The July 2025 Franco‑British summit in London marked a historic shift: coordinated nuclear deterrence between France and the UK through a formal nuclear supervision group, synchronised force postures, and strategic asset realignment. The Royal Air Force will buy 12 F‑35A jets, trained for nuclear strike with US B61 bombs—returning to airborne nuclear capability since 1998. This aligns with updated Lancaster House treaties, enhances Europe’s response to “extreme threats,” and preserves national sovereignty while allowing information sharing and operational alignment.
Franco-British nuclear coordination: framework and governance
During the bilateral summit held in London on July 10, 2025, French President Emmanuel Macron and British Prime Minister Keir Starmer confirmed the establishment of a formal structure dedicated to nuclear cooperation between France and the United Kingdom. This initiative introduces a “nuclear supervision group”, a joint oversight body reporting directly to both the Élysée and the British Cabinet Office. Its role will be to facilitate exchange of sensitive information, to bring coherence to strategic deterrence communication, and to ensure a consistent posture in the event of elevated threats.
This coordination does not involve merging operational commands. France and the UK will continue to maintain separate nuclear chains of command. France upholds its autonomous deterrent based on both air- and sea-launched platforms, including its nuclear-powered ballistic missile submarines (SNLE) and the Air-Sol Moyenne Portée (ASMPA) missile carried by Rafale fighters. The United Kingdom, for its part, remains committed to its Trident II D5 submarine-based system, operated from HMNB Clyde, and is now extending its capacity by integrating air-based nuclear delivery via newly acquired F-35A aircraft.
The new supervisory structure has been designed to coordinate decision thresholds, align posture escalation protocols, and provide a shared framework for crisis assessment and strategic calibration. It will serve as a communication channel for high-level decision-makers, particularly in cases where Europe may be exposed to what both parties described as a “situation of extreme threat.” In practice, this means that readiness levels can be increased in parallel, joint evaluations of adversarial intent can be carried out, and deterrent signals can be harmonised—while still leaving final decisions to each country’s elected leadership.
Although this format does not translate into joint command or automatic military response, it does formalise the political intent of closer coordination between the two most capable nuclear powers in Europe. The updated treaty framework, informally referred to as the Lancaster House 2.0 declaration, provides the legal and institutional scaffolding for this arrangement. It strengthens continuity with previous defence accords while adjusting to the evolving geopolitical context.
To illustrate, if intelligence assessments from either capital suggest an imminent strategic threat—whether cyber, conventional or nuclear—both governments may choose to elevate their respective nuclear postures. This could involve raising the alert status of submarine patrols or preparing aircraft capable of carrying nuclear payloads. However, each state retains exclusive national control over its forces and decision-making authority remains strictly sovereign.
This approach reflects a deliberate balance: enabling cooperation without dependency, and building trust without compromising autonomy. It is a model tailored for two nuclear-armed states facing a volatile international security environment, particularly in the context of increased Russian assertiveness and uncertainties over the reliability of broader transatlantic support.
RAF’s return to nuclear strike capability via F-35A acquisition
As part of a broader realignment of its strategic posture, the UK Ministry of Defence has confirmed the acquisition of 12 F-35A Lightning II fighter jets from Lockheed Martin. Unlike the vertical take-off F-35B already in British service, the F-35A is the only version currently qualified to carry the B61-12 tactical nuclear bomb, developed by the United States. This development marks a significant shift in the UK’s defence planning: for the first time in over two decades, the Royal Air Force will regain the capability to deliver nuclear weapons by air.
These aircraft will be stationed at RAF Marham, a key airbase located in Norfolk, which already supports British F-35 operations. The jets will be assigned to 207 Squadron, which serves as the Operational Conversion Unit responsible for pilot training and tactical readiness. The choice of this base simplifies logistics and training by leveraging existing infrastructure, while integrating nuclear certification protocols and new mission requirements.
From a technical perspective, the F-35A offers notable cost and operational advantages compared to the F-35B. Procurement costs for the A variant are estimated to be 15% to 25% lower, and operating expenses are around 8% cheaper per flight hour. This efficiency allows the UK to maintain high readiness levels without disproportionate budgetary impact. Additionally, the F-35A has a larger internal weapons bay and higher fuel capacity, which translates into greater mission flexibility and endurance.
Each aircraft is capable of carrying a B61-12 bomb in its internal bay without compromising its low-observability profile. This bomb features dial-a-yield technology, allowing variable explosive power, and enhanced accuracy thanks to a tail guidance kit. Integration certification for the F-35A was finalised in October 2023, making the aircraft fully compatible with NATO’s forward-deployed nuclear systems. This compatibility is crucial for potential deployments to European bases in allied countries under NATO’s nuclear sharing framework.
The move also has historical significance. The last time the RAF maintained an airborne nuclear delivery capability was in the late 1990s, when the WE-177 bomb—a free-fall weapon carried by Tornado and Buccaneer aircraft—was withdrawn from service. Since then, the UK’s nuclear deterrent has been solely submarine-based, delivered by Vanguard-class SSBNs armed with Trident II D5 missiles. The addition of air-based nuclear delivery restores a dual-domain strategy, strengthening deterrence through strategic ambiguity and operational redundancy.
In terms of training and maintenance, the F-35A is generally easier to support than the F-35B. It holds around 20% more internal fuel, extending its operational range. It also benefits from a simpler airframe design, reducing mechanical complexity and increasing aircraft availability rates. For RAF pilots, the switch to this variant requires additional qualification, particularly for nuclear strike protocols, but the transition is facilitated by existing experience with the B model.
Strategically, this acquisition signals a shift in how the UK approaches deterrence in a changing threat environment. The renewed emphasis on tactical flexibility, paired with long-range submarine patrols, offers a broader menu of response options in case of crisis. It also ensures interoperability with US and NATO forces, aligning with the broader objective of enhanced burden-sharing within the alliance.
By reintroducing this capability, the UK reinforces its role as one of Europe’s most capable military powers—one that maintains both sovereign decision-making authority and the capacity to act swiftly and independently in a high-threat scenario. It is not simply a matter of reviving an old function, but of adapting to a reality in which air-delivered deterrence plays a growing role in the politics of escalation control and defensive signalling.
Strategic context: deterrence posture and NATO sharing
The renewed Franco-British nuclear cooperation and the RAF’s re-entry into air-based nuclear delivery must be understood within the broader framework of NATO’s deterrence architecture. Central to this system is the Dual Capable Aircraft (DCA) programme, a NATO policy that enables select member states to host and operate aircraft capable of delivering US-owned nuclear weapons, specifically the B61 family of gravity bombs.
At present, it is estimated that around 150 B61 bombs are stored under US custody at six European bases, including locations in Germany, Italy, the Netherlands, Belgium, and Turkey. These weapons are intended for deployment aboard aircraft from participating host nations, under joint NATO protocols. By integrating F-35A aircraft—the only model currently certified for the B61-12 variant—the UK effectively joins this select group of dual-capable contributors, even though it has not hosted US nuclear weapons on its soil for decades.
The reintroduction of a British DCA element helps rebalance alliance deterrence at a time when concerns are growing over the nuclear posture of Russia, the modernisation efforts of China, and potential shifts in US commitment depending on domestic political outcomes. In particular, the possibility of reduced US military presence in Europe under a future Trump administration has prompted NATO members to increase redundancy and flexibility within their deterrence frameworks. The UK’s move adds another layer of credible response and helps distribute responsibilities more evenly across NATO’s nuclear planning.
Beyond posture alignment, this strategic recalibration includes updates to the Lancaster House agreements, the foundational Franco-British defence treaties first signed in 2010. These revised protocols now cover joint development of advanced cruise missile systems, with longer range and precision capabilities, as well as collaborative research into artificial intelligence applications in nuclear command and control. Such projects are designed to enhance long-term deterrence credibility while ensuring technological sovereignty within Europe’s two most advanced militaries.
The numbers speak for themselves: France and the UK together account for roughly 40% of total European defence expenditure, making them pivotal players in the continent’s military balance. Their joint leadership in nuclear matters reinforces this position. However, with that leadership comes added responsibility, especially in times of strategic ambiguity.
From an operational standpoint, British F-35As could—if required—be deployed to NATO’s forward operating bases, such as Kleine Brogel in Belgium or Ghedi in Italy, both of which are known to host US B61 bombs. These deployments would enhance the credibility of NATO’s deterrence signal, particularly in moments of regional crisis. Yet, it is essential to note that the use of these nuclear assets remains tightly controlled. The release authority lies with the United States President, in consultation with NATO’s Nuclear Planning Group, and the British Prime Minister, ensuring that no single actor can unilaterally decide on deployment or use.
This arrangement offers both flexibility and constraint. It allows for pre-planned options and coordinated escalation management, while maintaining the political threshold necessary to preserve deterrence credibility without triggering premature confrontation. It also reflects the high degree of trust between Washington, London, and other NATO capitals—trust that is essential to any functioning nuclear-sharing scheme.
Taken together, the UK’s integration of DCA assets, the joint Franco-British technological roadmap, and the reaffirmation of treaty-based cooperation underscore a shift toward a more autonomous but interoperable European deterrent capability. While firmly embedded in the NATO framework, this evolution acknowledges the real possibility of having to act decisively in the absence of consistent US leadership.
The implications and consequences for defence and geopolitics
1. Heightened deterrence posture: The UK unlocks air-based nuclear delivery after nearly 30 years, broadening response options. This dual-domain triad complicates adversaries’ strategic calculus .
2. Budgetary impact: Buying 12 F‑35As is estimated at around €100 million or €8.3 million per aircraft relative to the £80 million reported total . Operating costs and training will rise, though partially offset by B-variant economies. The UK defence spend aims to reach 2.6 % of GDP by 2027, from 2.3 %, with aspirations to meet NATO 5 % benchmarks by 2035 .
3. Industrial and alliance dynamics: Prior decisions postponed parts of the Global Combat Air Programme (GCAP) by Italy, Japan, and the UK. Integrating F‑35A may reorient industrial resources to US firms and complicate future European collaborative projects .
4. European strategic autonomy: France and UK’s cooperation may signal a path toward a distinct European nuclear umbrella, less reliant on the US . But practical implementation depends on political will, timely integration, and available infrastructure.
5. Escalation risks: Critics warn about lowering nuclear thresholds with tactical weapons deployment. B61‑12’s accuracy could make political leaders more willing to use them in crises—triggering escalation.
Areas requiring further attention
Approval and basing of US bombs: The UK government has not disclosed whether B61 bombs will be stored on UK soil or on French/NATO bases. This sensitive decision has local political and treaty implications .
Integration challenges: Pilots and support crews require nuclear certification, infrastructure upgrades at RAF Marham, and insertion into NATO command-and-control frameworks. That requires months of training and command protocols clarification.
Industrial balance: Shifts toward US-built jets may further delay Europeans’ next-generation capabilities. Countries like Germany and Italy may push for renewed European-led nuclear-capable platforms.
Internal political debate: Reintroduction of nuclear arms into the RAF will attract domestic criticism—from anti-nuclear advocates to cost-conscious parliamentarians.
The Franco-British agreement of July 2025 reflects a calculated, technical advance in European deterrence. By combining France’s fully nuclear-equipped forces with the UK’s revived airborne nuclear capability, they effectively create a resilient, layered nuclear posture. This framework enhances NATO’s burden-sharing, strengthens response options in crises, and signals contested geopolitical resolve.
However, the path forward needs careful handling: from storage deployment to operational integration, and managing alliance tensions between US and European defence initiatives. As both nations work to avoid relying solely on US nuclear umbrella, this initiative both extends deterrence credibility and surfaces the challenges of maintaining Western strategic balance.