The Lancaster House Treaties: 10 years of Franco-British defence partnership


The Lancaster House Treaties, signed on 2 November 2010, are a cornerstone of the firm defence and security partnership between our two countries. This defence cooperation is founded upon common interests and a shared determination to defend the international order and a multilateralism based on democratic and universal values. It rests on a shared vision and a longstanding strategic proximity.

As we mark the 10th anniversary of the Treaties, France fully intends to pursue a structuring bilateral defence cooperation in all areas over the coming years: operational, capability, industrial and nuclear. This cooperation will continue on the basis of a close dialogue on all defence and international security related issues, to consolidate the privileged defence relationship developed with the United Kingdom, and maintain a high level of ambition in the coming years.

The domains of Franco-British cooperation

For the last 10 years, thanks to the Lancaster House Treaties, the Franco-British cooperation has been reinforced particularly in the operational and nuclear domains as well as in terms of military capabilities.

  • As regards operations, the Combined Joint Expeditionary Force (CJEF) was declared fully operational this year. CJEF is a binational force counting up to 10,000 troops, deployable at short notice and able to conduct high-intensity operations. France and the United Kingdom also work together in the field. Our two countries cooperate in theatres of crisis, in the Sahel in Operation Barkhane and in the Levant. They also participate in NATO operations on the European continent (Enhanced Forward Presence in the Baltic countries, Baltic Air Policing mission).
  • In terms of military capabilities, Franco-British armaments cooperation has been structured in the missile field around information-sharing relating to research and needs, in order to identify the axes of our future cooperation and to streamline costs. The Future Cruise and Anti-Ship Weapon (FC/ASW) joint project is at the core of our common priorities and could enter its assessment phase in early 2021. The Maritime Mine Counter Measures (MMCM) joint project has also made significant progress since 2015.
  • The Franco-British nuclear cooperation inscribed in the Lancaster House Treaties is structured especially by the Teutates Treaty, which aims at sharing the radiographic facilities relating to the deterrence programmes of both countries and which will be continued in the years to come.
Read the joint interview by French Ambassador to London Catherine Colonna and British Ambassador to Paris Ed Llewellyn, first published in la Revue de la Défense nationale on 2 November 2020.