The move appears to offer both countries’ nuclear weapons as a deterrent for all of Europe while establishing greater independence from any safety net provided by the U.S.’s much larger arsenal.

Britain and France will join together to use nuclear weapons against any “extreme threats” towards Europe, Sir Keir Starmer and Emmanuel Macron have declared. A newly-signed declaration by the leaders will state that the two countries’ nuclear deterrents are independent but can be co-ordinated in a joint attack on Europe’s enemies.