Q&A: UK-French defence treaty
What is happening?
David Cameron has hosted a one-day summit with French President Nicolas Sarkozy in London. They have signed two treaties - one is described as a far-reaching agreement on military co-operation, the other is a 50-year deal on the testing of nuclear weapons.
Why are they signing a deal now?
Both countries want to remain global defence powers. Spending cuts mean they are willing to pool resources to achieve that end. Defence Secretary Liam Fox told the BBC that between them the UK and France accounted for 50% of Europe's defence spending - and about 65% of research and development spending. He said it made sense to work together to ensure greater value for money. Britain also says that President Sarkozy's decision to take France back into Nato's military command played a part - Dr Fox said the UK wanted to build on that.
What will greater military co-operation mean?
From next year, there will be joint training exercises with British and French troops, to prepare them for a new rapid reaction force. This is not a fixed joint brigade but will be drawn upon as needed, from a designated pool of troops in both countries. It will be deployed by a joint political decision, under a single British or French commander. An agreement on the aircraft carriers, which spend about 30% of their time undergoing refits, means that when France's Charles de Gaulle carrier is out of service, Britain's operational carrier will be made available for French personnel, both to keep up training and potentially to use in a military operation - if Britain agrees. The reverse would happen when the UK's carrier is out of service. The two countries will also pool resources for the training, maintenance and logistics of the new A400M transport aircraft, which both are acquiring. There are also longer term plans for joint working on a range of programmes, including satellite communications, cyber security, developing new missile systems and unmanned aerial drones.
What joint nuclear work will happen?
There will not be joint patrols or nuclear weapons but there will be two new facilities which will be shared, but with separate areas, to test British and French nuclear warheads at the Atomic Weapons Establishment at Aldermaston and its French counterpart at Valduc. Some British scientists will be based in Valduc and French scientists in the UK - testing will be carried out in France and the technology will be developed in the UK. The two countries will work together on a new hydrodynamic facility, which ensures warheads are working properly. They are tested by technical means to ensure their safety and effectiveness without having to detonate them. Both France and the UK have said they will abide by the Test Ban Treaty which forbids such explosions even though formally the treaty has not yet come into force. However nuclear secrets will not be shared or the merging of Britain and France's nuclear weapons systems. BBC political editor Nick Robinson said testing nuclear components together would cost British jobs.
Will Britain and France be dependent on each other?
They say not. But Labour has suggested the treaty could "usher in an era where we are reliant on our allies to fill the gaps in the government's defence policy". There has also been some unease in the UK about the idea of British troops being commanded by French officers. The UK's defence secretary says that can already happen in Nato operations and insisted UK defence would remain "sovereign" and the countries would "operate together when it's in our interest to do so but retain our capabilities to act independently when our nations require it".