The latest round in the fight over the future of the UK armed forces is raging in the corridors of Whitehall. As politicians and military top brass argue about money, wider questions about what we want the Army, Navy and RAF to do once again top the defence agenda.

Caroline Wyatt spent many years covering defence for the BBC and has heard warnings from retired generals about chronic under-funding many times. But with army numbers already down to a level not seen since before the Napoleonic Wars, big projects like the F-35 fighter jets in trouble, and a £2bn a year black hole in the defence budget, further salami slicing seems untenable. How then to prioritise which capabilities the UK must maintain and improve?

The UK faces an intensified threat from Russia, 'hybrid' warfare where cyber attacks and political destabilisation are used alongside military force, and advances in missile technology. Post Brexit, the UK's strategic position both globally and within the European defence space is unclear. How we want to deploy our armed forces - where, with whom, and at what cost - is once again up for debate.

Producer: Lucy Proctor.