The U.K. and France will agree to strengthen their cooperation on nuclear deterrence, formally declaring a willingness to coordinate any response to an extreme security threat in Europe.

The two nuclear-armed members of the U.N. Security Council will highlight deeper defense ties during meetings between U.K. Prime Minister Keir Starmer and French President Emmanuel Macron on Thursday in London. They will also order more of the conventionally armed Storm Shadow cruise missiles that they’ve been supplying to Ukraine and accelerate efforts to develop a next-generation replacement for the weapons, according to a statement from the British defense ministry.

The announcement — made during a state visit to the U.K. by Macron — is part of an attempt by both leaders to signal their commitment to Europe’s sovereign defense capabilities amid the threat from Russia as the U.S. signals a desire to pare back its traditional security role in the continent under President Donald Trump.

“From war in Europe to new nuclear risks and daily cyber attacks, the threats we face are multiplying,” Starmer said in the statement. “As close partners and NATO allies, the U.K. and France have a deep history of defense collaboration and today’s agreements take our partnership to the next level.”

Starmer and Macron are also expected to announce a new plan to tackle migrant crossings on the English channel on Thursday. Le Monde reported that France would only accept the return of up to 50 migrants per week under the agreement, a relatively small share given that 695 migrants arrived across the channel to the U.K. this past week. Defence Secretary John Healey didn’t deny the contents of the report on Thursday.

A series of other Anglo-French projects on air-to-air missiles, directed energy weapons, space and artificial intelligence will also be advanced, under the badge of a new “Entente Industrielle” — a play on the Entente Cordiale, a set of early 20th-century agreements designed to improve relations between the historic adversaries. Healey said the two militaries will increase coordination, allowing a force of around 50,000 to be ready to activate and defend Europe within NATO.

The further commitment to the Storm Shadow program, and the step closer to choosing a final design for its successor deep strike missile, comes after the weapon was deployed by Ukraine to strike targets inside Russia.

Starmer and Macron are to dial in to a meeting of the so-called Coalition of the Willing on Thursday, a group of countries that have pledged continued support for Ukraine. A senior French official said a representative from the U.S. — although not Trump himself — would also join the call, in a further sign of American backing for the country just a day after the president vowed to resume halted weapons deliveries.

The coalition will announce that it has an operation command center on that call, the official said.

Known as SCALP in France, Storm Shadow missiles have a maximum range of around 250 kilometers (160 miles). They are produced by the multinational European arms maker MBDA and are seen as having exceptional accuracy because of their advanced navigation system.

The missiles fly close to the terrain at high speeds and using a combination of so-called inertial navigation with Global Positioning System and terrain-reference navigation, according to a fact-sheet on the MBDA website. Each missile costs almost $1 million. The U.K. government did not say how many it would order nor whether they are to replenish domestic stocks or to send on to Ukraine.

Britain began allowing Ukraine to use Storm Shadow against targets inside Russia in November 2024, following a decision by then U.S. President Joe Biden to approve Kyiv’s limited use of the weapons to hit military sites on Russian territory.

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—With assistance from William Selway.

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