France and the United Kingdom have signed a pact to coordinate on nuclear weapons deployment in response to heightened security threats to Europe.
French President Emmanuel Macron and British Prime Minister Keir Starmer announced the agreement after a July 2025 summit in the U.K. Under the agreement, the two nations are “confirming for the first time that we are coordinating our independent nuclear deterrence,” Starmer said during a news conference at Northwood, a military headquarters northwest of London, according to Reuters. “From today, our adversaries will know that any extreme threat to this continent would prompt a response from our two nations,” Starmer said. “There is no greater demonstration of the importance of this relationship.”
The countries created an oversight committee to coordinate policy, capability and operations, Macron said. No two other countries had “this closeness on nuclear doctrine,” he said, and the pact is a “message our partners must hear, as well as our adversaries.”
The agreement also includes plans to jointly develop next-generation long-range missiles, including deep-strike and anti-ship missiles, to replace the current Storm Shadow cruise missiles.
In a U.K. government declaration, leaders called the agreement Lancaster House 2.0, building on the 2010 Lancaster House treaties between France and the U.K. that called for sharing of equipment and technology related to joint stewardship of nuclear stockpiles. In addition to coordination of nuclear forces and nuclear research, the new agreement calls for enhancing combined force capabilities to “facilitate the deployment of a force fully interoperable with NATO and available as the Alliance’s strategic reserve,” according to the statement. The agreement also aims to grow the defense-industrial base.
“We agree to deepen and broaden our unique defense and security partnership … complementing our cooperation in NATO and reinforcing Europe’s contribution to it, as well as the UK-EU [European Union] Security and Defence Partnership,” the statement read. “As Europe’s two nuclear powers and leading militaries, we share responsibility for the continent’s defense and security. We are united in the face of profound security threats and challenges, in particular the immediate and pressing threat posed by Russia to Euro-Atlantic security.”
The two leaders also acknowledged that threats in the Indo-Pacific affect Europe, and the two nations will establish a global maritime security dialogue to address security challenges from China, North Korea and Russia. “We will strengthen our coordination and work together for a free, open and sovereign Indo-Pacific through new joint maritime security training, reciprocal base access, and joint support to regional organizations,” the declaration reads. “We jointly reaffirm our commitment to peace and stability in the Korean peninsula, in the South and East China Seas, and in the Taiwan Strait, where we call for the peaceful resolution of cross-Strait issues.”
In addition to coordinating nuclear deterrence forces, France and the U.K. each have announced plans to increase their own defense spending. Macron said France will double its defense budget by 2027, three years earlier than originally planned, according to BBC News. “To be free in this world, you must be feared. To be feared, you must be powerful,” Macron said during a speech to the French Armed Forces in Paris on the country’s Bastille Day holiday.
Starmer announced at the June 2025 NATO summit at The Hague that the U.K. will buy 12 United States-made F-35A fighter jets capable of carrying nuclear bombs and will join NATO’s shared airborne nuclear mission, according to The Associated Press.
“In an era of radical uncertainty, we can no longer take peace for granted, which is why my government is investing in our national security,” Starmer said in a statement. The government called the purchase the “biggest strengthening of the U.K.’s nuclear posture in a generation.”