A European Nuclear Backstop: Exploring France’s Potential Extended Deterrence

Introduction

France’s March 2025 announcement of a fourth nuclear-capable airbase at Luxeuil Saint-Sauveur near the German border signalled potential expansion of French nuclear protection beyond national boundaries.¹ The August 2025 Franco-German Defence Council conclusions explicitly acknowledged that France’s nuclear forces contribute to Alliance security, committing both governments to strategic dialogue². These developments occur against the backdrop of acute European vulnerability. Russia possesses approximately 5,580 nuclear warheads, while EU member states collectively possess none.³ The United Kingdom maintains independent forces but remains outside EU structures and embedded within American planning systems.⁴ European conventional spending increases, including Germany’s 600-billion-euro commitment, cannot address this fundamental nuclear asymmetry (German Marshall Fund, 2025).

This brief examines how French extended deterrence relates to European political integration through four questions: What credibility requirements does extended deterrence impose? How do these requirements reshape institutional relationships between France and potential partners? What integration dynamics might nuclear cooperation generate compared to economic cooperation? Can such arrangements prove sustainable beyond President Macron’s tenure?

The Strategic Context

US commitments to Europe are weakening as Washington increasingly prioritises the Indo-Pacific and political change at home makes long-term security guarantees less predictable.⁵ This uncertainty has grown sufficiently acute that Germany’s defence leadership now prepares contingency plans for scenarios involving significantly reduced American continental presence (German Marshall Fund, 2025). European states recognise that conventional military expansion cannot substitute for nuclear protection. Despite Poland increasing its defence spending to 3–4 percent of GDP and Italy meeting NATO targets, adversaries possessing nuclear weapons retain a nuclear advantage regardless of conventional force balances .⁶ Russia’s explicit nuclear threats during the Ukraine conflict confirmed what strategic theory predicted: conventional superiority becomes strategically irrelevant when adversaries can credibly threaten nuclear employment.

This vulnerability explains Poland’s exploration of indigenous nuclear capabilities.⁷ Yet national proliferation would fragment European security architecture while potentially triggering additional member states to reconsider nuclear abstinence, ultimately undermining global efforts to limit nuclear spread.⁸ French extended deterrence thus emerges as an alternative framework that addresses collective European vulnerabilities without the destabilising consequences of fragmented national programmes.

Analysing Deterrence Credibility

Extended nuclear deterrence works by making opponents uncertain about the consequences of an attack, not by matching weapons one-for-one.⁹ An adversary does not need certainty of retaliation, only a strong belief that the risk would be unacceptably high.¹⁰ This logic sustained American extended deterrence throughout the Cold War despite persistent debates about whether Washington would sacrifice American cities for European allies.¹¹ The French force structure provides the foundation for credible extended deterrence. Four Triomphant-class submarines conduct continuous at-sea patrols, ensuring the ability to retaliate after a first strike, complemented by Rafale aircraft equipped with ASMP-A cruise missiles offering flexible response options.¹² The M51 submarine-launched missile’s range exceeding 9,000 kilometres enables strikes against strategic targets from North Atlantic patrol areas.¹³ France follows a doctrine based on maintaining only the minimum nuclear forces it considers necessary, contending that the capability to inflict unacceptable damage provides deterrence regardless of force ratios.¹⁴ 

Geography makes this deterrent more credible in Europe than it was during the Cold War between the US and the Soviet Union.¹⁵ Poland’s eastern border sits merely 1,400 kilometres from Paris, meaning Russian operations threatening Eastern Europe would necessarily approach French territory and create potential automatic escalation. Macron’s decision to position nuclear-capable infrastructure at Luxeuil-Saint-Sauveur near Germany physically couples French security with German defence.¹⁶ Yet credibility ultimately depends on political commitment beyond military capability and geographic proximity.¹⁷ Deterrence effectiveness requires adversaries believing that protecting states would risk nuclear exchange defending allied territory, a conviction emerging substantially from confidence that alliance mechanisms would trigger a collective response.¹⁸

Historical Precedent and Institutional Dynamics

NATO’s Nuclear Planning Group, established in 1966, provided non-nuclear member states institutional participation in alliance nuclear policy while preserving American ultimate decision authority (Heuser, 1997). Germany, Italy, Belgium, the Netherlands, and Turkey hosted American nuclear weapons through arrangements that enhanced deterrence credibility by demonstrating alliance commitment while granting non-nuclear states a meaningful institutional voice.¹⁹ West Germany’s experience illuminates the dynamics of extended deterrence arrangements. Bonn insisted on being formally consulted as a condition for hosting American nuclear weapons, ultimately gaining significant influence over NATO nuclear policy despite lacking independent weapons.²⁰ This reflected a fundamental recognition: American extended deterrence credibility required visible commitment from protected states, which necessarily granted those states leverage over provider policies.²¹ The arrangement generated mutual dependencies constraining both provider and recipients rather than creating purely hierarchical relationships.

More recent precedent reinforces these lessons. The 2010 Lancaster House Treaties established Franco-British nuclear cooperation, including shared simulation facilities and joint technology development, while both states maintained completely independent deterrents and separate chains of command.²² This demonstrates that even states maintaining fiercely independent nuclear forces can deepen coordination through institutional frameworks without compromising sovereignty over ultimate employment decisions.²³

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Institutional Mechanisms and Integration

Extended deterrence frameworks could take multiple institutional forms depending on political willingness and operational requirements. One approach involves a formal consultation process modelled on NATO’s Nuclear Planning Group, adapted to reflect EU institutional norms.²⁴ France and participating member states could establish a European Strategic Nuclear Council providing regular forums for discussing nuclear doctrine evolution, threat assessments, and crisis communication procedures. France would retain sole employment authority to preserve deterrence credibility, but Council deliberations could inform how France deploys and manages its nuclear forces and strategic communications in ways that enhance credibility through demonstrating European political commitment. 

Shared financing arrangements would create material interdependence, reinforcing political commitment.²⁵ Participating states could contribute to infrastructure supporting deterrence effectiveness, including hardened command facilities, secure communications networks, cyber defence systems protecting nuclear command and control, and intelligence fusion capabilities supporting strategic early warning. Germany’s existing space-based reconnaissance capabilities and Poland’s developing eastern flank monitoring systems could provide concrete operational contributions beyond financial transfers, creating an integrated infrastructure that enhances collective security. Rotational deployments of French strategic command elements to Eastern European states could address regional security concerns without requiring permanent nuclear weapon basing that might prove escalatory.²⁶ Command staff and communications equipment could integrate French nuclear planning with local conventional forces, putting in place systems that would almost certainly trigger wider conflict if a host country were attacked.

These institutional mechanisms raise fundamental questions about European integration dynamics. Economic integration permits member states to exit arrangements when costs exceed perceived benefits, limiting integration depth.²⁷ Nuclear cooperation potentially creates qualitatively different dynamics.²⁸ Countries that rely on protection agreements become fundamentally dependent on them for their security, where exit means accepting strategic vulnerability, potentially generating deeper political integration than economic cooperation has achieved over seven decades.²⁹ However, substantial challenges complicate implementation. Some member states maintain neutrality commitments that complicate participation in explicit nuclear frameworks.³⁰ Ireland, Austria, Malta, and Cyprus would likely remain outside any such architecture, given constitutional constraints and political traditions. Political resistance exists in multiple states concerned about potential French influence over European security policy.³¹ German domestic anti-nuclear sentiment, rooted in peace movement traditions, could constrain government participation despite strategic logic potentially favouring cooperation.³² Eastern European states might question whether French protection provides equivalent credibility to American extended deterrence, given differences in geographic proximity and historical security relationships.³³

Coordination with NATO structures presents additional institutional complexity.³⁴ European nuclear frameworks must complement rather than duplicate or undermine existing alliance arrangements that continue providing collective defence. Mechanisms linking a European Strategic Nuclear Council to NATO’s Nuclear Planning Group would require careful development to prevent conflicting guidance during crises. American reactions to European nuclear cooperation remain uncertain and could range from supporting European assumptions of greater defence responsibility to perceiving such arrangements as weakening transatlantic ties.³⁵

Sustainability Beyond Macron

French extended deterrence sustainability depends critically on whether arrangements reflect structural French interests rather than personal Macron initiatives. Evidence suggests deeper foundations than individual presidential preferences. French nuclear doctrine evolution toward acknowledging European dimensions predates Macron, visible in strategic reviews from previous administrations.³⁶ France’s geographic position, embedding it within continental security dynamics, industrial base reliance on European markets, and political influence within EU institutions create enduring interests in European security architecture that transcend electoral cycles. However, political sustainability faces genuine challenges rooted in French strategic culture. 

Significant Gaullist traditions emphasise pure national independence in nuclear matters, creating domestic resistance to institutional constraints on French strategic autonomy. Right-wing political forces potentially gaining power in the 2027 elections have historically opposed such constraints,³⁷ while left-wing coalitions supporting European integration often face anti-nuclear constituencies, complicating nuclear cooperation frameworks. Yet several factors could enhance sustainability beyond Macron’s presidency. Treaty frameworks ratified by the French parliament create legal obligations binding successive governments, while financial commitments from participating European states generate material dependencies, making unilateral French withdrawal politically costly. Deployed command elements would establish operational integration, difficult to reverse without disrupting French force posture.³⁸

Germany’s recent strategic transformation provides a crucial supporting factor. Chancellor Merz’s government suspended constitutional debt restrictions for defence, signalling a fundamental shift in German strategic culture rather than a temporary adjustment (German Marshall Fund, 2025). If German commitment persists beyond the current government, French extended deterrence arrangements could gain momentum, transcending individual presidencies in either country.

Eastern European demand for alternatives to uncertain American commitments provides additional sustainability pressure. Polish exploration of indigenous nuclear capabilities reflects security concerns unlikely to dissipate with American political cycles.³⁹ French extended deterrence offers a mechanism addressing collective European vulnerabilities, creating demand-side pressure sustaining arrangements regardless of French domestic political transitions.

Conclusion

French extended deterrence presents complex strategic dynamics with multiple implications for European political integration. The framework could address European nuclear vulnerability at a moment when American commitment faces structural uncertainty, while geographic proximity between France and potential threat scenarios provides different credibility foundations than Cold War transatlantic extended deterrence. Historical precedent from NATO’s Nuclear Planning Group and Franco-British cooperation demonstrates that nuclear cooperation among sovereign states can function through institutional mechanisms balancing operational requirements with political legitimacy. 

However, substantial obstacles complicate potential implementation. Political resistance to French influence, constitutional constraints in neutral member states, domestic anti-nuclear sentiment in key countries, including Germany, and coordination challenges with NATO structures all require careful navigation. The integration dynamics remain fundamentally uncertain: nuclear cooperation could create deeper interdependencies than economic integration driven by security arrangements that lock countries into long-term commitments, or alternatively, political opposition could block the creation of effective institutions, leaving European security fragmented.

Sustainability beyond Macron’s presidency depends on whether arrangements reflect structural French interests in European security architecture or personal presidential initiatives. France’s geographic position, economic integration with European partners, and political influence within EU institutions suggest enduring strategic interests. Yet domestic political traditions emphasising nuclear independence and potential right-wing governments in 2027 pose genuine challenges. Institutional mechanisms, including treaty frameworks ratified by parliament, financial commitments from participating states, and operational integration through deployed command elements, could enhance durability across presidential transitions.

About the Authors

Jacopo Damaschi

Research Associate

Jacopo is a Research Associate at Hegemoniq. He holds an MSc in European and International Politics and Policy from the London School of Economics (LSE) and a BA in International and Diplomatic Sciences from the University of Trieste.

Sanchita Sinha Research Intern

Contributed extensive research and data analysis to this brief on the European Nuclear Backstop.

Disclaimer

The views and opinions expressed in this policy brief are those of the authors and do not necessarily reflect the official policy or position of Hegemoniq.

Endnotes

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