Deeper complex weapon and nuclear collaboration among high points of Lancaster House 2.0 accord between UK and France

The United Kingdom and France are to order more Storm Shadow/SCALP cruise missiles while stepping up work on the weapon’s replacement as part of a new refreshed Lancaster House agreement signed on 10 July 2025.

The new agreement will see the UK and France commit to launching the next phase of their joint project for both deep strike and anti-ship missiles: a step closer to selecting a final design for Storm Shadow’s replacement.

Meeting in London on 9-10 July, UK Prime Minister Keir Starmer and French President Emmanuel Macron also agreed to deepen their nuclear co-operation and work more closely than ever before on nuclear deterrence amid a myriad of new bilateral initiatives.

The UK and France are Europe’s only nuclear powers, with deterrents that contribute significantly to the overall security of NATO and the Euro-Atlantic.

The original Lancaster House Agreement on defence and security co-operation between the UK and France was signed at 10 Downing Street on 2 November 2010 by UK Prime Minister David Cameron and French President Nicolas Sarkozy.

The new ‘Lancaster House 2.0’ agreement, signed by Starmer and Macron at 10 Downing Street on 10 July, states that the two countries will:

• Deepen their longstanding and resolute commitment to co-operation between their independent nuclear deterrents;
• Launch the Combined Joint Force, which overhauls the existing Combined Joint Expeditionary Force to refocus it on the Euro-Atlantic and warfighting at scale, placing it on an operational footing for the first time, enhancing its capabilities by “up to fivefold” and allowing it to command a Combined UK/French Corps for the first time;
• Embark upon an ‘Entente Industrielle’ to enhance capability and industrial co-operation, bringing the two countries’ defence industries and militaries closer than ever before to strengthen NATO.
• Develop new co-operation in every domain to enhance military interoperability and support NATO, driven by annual meetings of the two countries’ joint chiefs;
• Reinforce the UK-French integrated defence and security partnership to deter and respond to the full spectrum of threats;
• Enhance communications and institutional exchanges across the two countries’ systems as an enabler to a strengthened partnership across the entirety of defence and national security.

The Entente Industrielle in particular will see several measures taken with regard to future weapon procurement and development. Specifically, the two nations will:

• Launch the development phase of the Future Cruise and Anti-Ship Weapon (FC/ASW) programme to provide the next generation of long-range, highly survivable deep strike missiles;
• Jointly develop the next generation of beyond-visual-range air-to-air missiles (BVRAAMs) for UK and French fighters, while also extending the capability of the Meteor BVRAAM, launching a joint study with industry to inform the future development of its successor;
• Acquire new Storm Shadow/SCALP missiles following their successful use by Ukraine, upgrading UK and French production lines to bolster national stockpiles to deter adversaries;
• Establish a new, joint Complex Weapons Portfolio Office, embedded within the Organisation for Joint Armament Cooperation (OCCAR), through which the UK and France will deliver joint projects within OCCAR, starting with Storm Shadow/SCALP acquisition, and also work closely with the missile’s manufacturer, MBDA, to identify the opportunities from UK/French investments, reduce duplication, conduct studies on air dominance and co-operative strike future capabilities;
• Focus greater efforts on integrated air and missile defence (IAMD), including but not limited to counter-unmanned aerial system and counter-hypersonic capabilities, drawing especially from the Aster family of missiles, including potentially the SAMP/T NG and CAMM air defence systems;
• Continue to work closely on current and future long-range strike capabilities through the European Long Range Strike Approach (ELSA) initiative;
• Develop a directed-energy weapon partnership, sharing information, collaborating on research and projects of shared interest and exploring industry collaboration on radio-frequency weapons;
• Collaborate on developing algorithms for synchronised missile and drone strikes using artificial intelligence and machine learning,to build future interoperability;
• Explore a combat air interoperability roadmap, including potential collaboration on armaments, to support the connectivity and interoperability of current and future combat air forces and their contribution to European and NATO air superiority;
• Commit to aligning standards for weapons safety and testing, to bring operational benefits and save time and money in joint programmes;
• Work closely together on wider export campaigns for UK-French capabilities and establishing a new joint team, with an initial focus on supporting the export of A400M airlifters and identifying further concrete areas for joint export promotion;
• Recognise the importance of improving European defence-industrial resilience by enhancing reciprocal market access in defence and security.

Starmer said of the Lancaster House 2.0 agreement, “From war in Europe to new nuclear risks and daily cyber-attacks, the threats we face are multiplying. As close partners and NATO allies the UK and France have a deep history of defence collaboration and today’s agreements take our partnership to the next level. We stand ready to use our shared might to advance our joint capabilities – equipping us for the decades to come while supporting thousands of UK jobs and keeping our people safe.”

UK Defence Secretary John Healey added, “The UK and France are stepping up together to meet today’s threats and tomorrow’s challenges. We are committed to driving defence as an engine for growth, delivering better fighting capabilities faster, and ensuring our armed forces can operate side by side – from the High North to the Black Sea. This partnership strengthens our leadership in Europe, ensures continued support for Ukraine, and sends a clear signal to our adversaries that we stand stronger, together.”

A spokesperson for MBDA, which lies at the very heart of UK-French co-operation on complex weapons, told ESD on 11 July, “MBDA welcomes the joint commitments made by the United Kingdom and France on the occasion of the Franco-British summit in order to strengthen their common defence capabilities. The Complex Weapons domain and MBDA are confirmed as a central pillar of the bilateral co-operation and are at the heart of a new ‘Entente industrielle’ between both countries.”