Strategic Solidarity: A Proposal for Anglo-French Cooperation on Air-Launched Nuclear Systems

The Euro-Atlantic security architecture is currently navigating a geopolitical tipping point, characterized by the return of high-intensity conflict to the continent and the crumbling of the international rules-based order. The United States is signaling a potential reordering of its national priorities away from NATO and toward the Indo-Pacific, highlighting the need for a stronger European contribution to NATO’s nuclear deterrent. This reordering leaves the two European nuclear powers, the United Kingdom and France, to fundamentally reassess their partnership.

At the same time, Russia continues to expand its theater nuclear advantage over NATO by developing and fielding more systems capable of delivering nuclear weapons from air, sea, and land across battlefield and theater ranges, taking advantage of its vast arsenal of non-strategic nuclear weapons (NSNW).¹

To address the theater nuclear asymmetry between Russia and NATO, the United Kingdom and France must move beyond the consultations established under the Lancaster Treaty, the Northwood Declaration,² and France’s new nuclear doctrine, entering a new era of practical bilateral cooperation in the development of nuclear weapons and delivery systems.

This proposal advocates for the joint development of the Air-Sol Nucléaire de 4e Génération (ASN4G), France’s future nuclear air-launched cruise missile (ALCM-N), together with the associated Tête Nucléaire Aéroportée de 4e Génération (TNA4G) nuclear warhead. Crucially, while France would retain sovereign command over its nuclear forces, the United Kingdom could serve as a bridge between France and the Alliance by acting as an intermediary with NATO’s Nuclear Planning Group (NPG). Under this arrangement, the UK would earmark 100 or more nuclear-armed ASN4G missiles for NATO Allies to operate on certified dual-capable aircraft (DCA), thereby strengthening the European pillar of NATO’s nuclear deterrence and providing a hedge against potential future disruptions in US support for the Alliance.

To ensure long-term resilience, this cooperation should also extend to technical hedging for the sea-based deterrent. Specifically, it should incorporate modular designs for nuclear-powered ballistic missile submarines (SSBNs) that would allow the United Kingdom to pivot between US and French delivery systems if necessary.

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