The UK faces its greatest security threat since the Cold War and must prepare for the possibility of a prolonged war, the head of the armed forces has warned. Chief of the Defence Staff Sir Richard Knighton told the BBC's Today programme that the first five months of this year have seen as many incursions by Russian strategic aircraft into UK airspace as were recorded in the whole of 2025.
Sir Richard described last year's Strategic Defence Review as a 'call to arms', saying that while the armed forces have spent the last few decades preparing for short, localised conflicts, the UK now needs to be ready for protracted wars such as the one in Ukraine. 'I'm very clear that this is the most dangerous time I have known in my working life,' he said.
He warned that Russia was testing the UK through both traditional military defences and cyber attacks, sabotage and assassination attempts. 'So Russia is definitely raising the stakes and risks crossing a line,' he added. Sir Richard also spoke about the need to adapt to the changing nature of warfare, where drones and autonomous systems will play an increasingly important role.
His comments come ahead of the expected publication of the Defence Investment Plan, which will set out defence spending over the next decade. In February, Sir Richard and his German counterpart, General Carsten Breuer, said there is a 'moral' case for rearming against the threat of Russia and called for increased defence spending.
In a joint letter, the pair warned that Russia has 'shifted decisively westward' amid its invasion of Ukraine and said there was a need for a 'step change in our defence and security' across Europe. They wrote: 'There is a moral dimension to this endeavour. Rearmament is not warmongering; it is the responsible action of nations determined to protect their people and preserve peace. Strength deters aggression. Weakness invites it.'
