The UK and France will declare that the two nations’ nuclear deterrents, while independent, can be co-ordinated and that they will jointly respond to any “extreme threat to Europe,” both countries said Wednesday.

The declaration, to be signed Thursday, will state that the respective deterrents of both countries remain under national control “but can be co-ordinated, and that there is no extreme threat to Europe that would not prompt a response by both nations,” the UK’s Ministry of Defence (MoD) and the French presidency said in a statement.

French President Emmanuel Macron will sign the agreement Thursday as he wraps up his three-day state visit to the UK with a bilateral summit, where the allies will “reboot” defence ties with a focus on joint missile development and nuclear co-operation.