Britain and France are to order more Storm Shadow missiles as they step up work to replace the weapon as part of a refreshed defence pact.
Storm Shadow, known as SCALP in France, is a long-range missile that has been supplied by both nations to Ukraine, allowing Kyiv to strike targets deep inside Russian territory.
The two countries have discussed cooperation on a replacement for years, but, as French president Emmanuel Macron visits the UK, the nations will commit on Thursday towards the next phase of the project for Storm Shadow's successor.
The joint development will help sustain more than 1,300 jobs in the UK, according to the Government.
On the third day of Macron's UK state visit, he and Sir Keir Starmer (Labour) will also agree to deepen nuclear ties.
Britain and France, the only two nuclear powers in Europe, will state in a declaration that their nuclear deterrents can be coordinated while remaining independent, with the aim of deterring threats like Russia from attacking Europe.
The declaration comes as Donald Trump's US administration calls on European NATO powers to take on a larger role in the alliance.
Prime Minister Sir Keir Starmer said: "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.”
Defence Secretary John Healey said the UK and France are "stepping up together to meet today's threats and tomorrow's challenges".
He added: "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."
Building on the 2010 Lancaster House treaties between France and the UK, the two countries will also bolster a shared military venture known as the Combined Joint Force.
They plan to forge closer military industrial ties, including in artificial intelligence and direct energy weapons, as part of a programme dubbed the "Entente Industrielle" by the UK Government.
(PA/London) Note: This article has been edited with the help of Artificial Intelligence.
