David Cameron has today signed new treaties on defence and nuclear co-operation with France marking a new chapter in a long history of defence co-operation.
One treaty concerns nuclear technology with, a centre to be set up in the UK to develop nuclear testing technology and another in France to carry it out.
The other treaty will allow the setting up of a "combined joint expeditionary force", thought to involve a brigade of about 5,000 soldiers from each side which will operate under one military commander to be chosen at the time.
The UK and France have also agreed to keep at least one aircraft carrier at sea between them at any one time. Each will be able to use the other's carrier in some form, certainly for training and possibly operations.
David Cameron said: "Today we open a new chapter in a long history of co-operation on defence and security between Britain and France. It is about defending our national interest. It is about practical, hard-headed co-operation between two sovereign countries.