The head of the UK's armed forces has declared that Britain is facing its most perilous moment since the Cold War, as Russia intensifies hostile activity ranging from cyber attacks to aerial incursions.
“This is the most dangerous period that I have known,” Chief of the Defence Staff Sir Richard Knighton told BBC Radio 4’s Today programme. “The risks and threats to this country are greater than I have known since the Cold War.”
“Military chief Sir Richard Knighton warns Russia threats to UK are highest since Cold War”
Russia has been “probing, challenging, testing our defences”, Sir Richard said, and “raising the stakes and risks crossing a line” through cyber attacks, assassination attempts, smuggling technology and reckless sabotage, he added.
His warning comes just weeks before the long-delayed Defence Investment Plan is expected to be published. The prime minister said the document would be released before a Nato summit “in just a few weeks’ time”. Sir Keir Starmer said: “We’ve been working on that defence investment plan for some time, very closely with our armed forces.”
Sir Richard said that while the UK had prepared for short, contained conflicts in recent decades, it now needs to be ready for longer wars like the one in Ukraine. “What we need to ready ourselves for is potentially much greater, longer conflicts,” he told the BBC.
He highlighted increased Russian long-range aviation activity in the High North, which includes the Arctic circle. “Closer to home we have seen in 2026 more long-range aviation from Russia. These are strategic aircraft that will go well into our own airspace. We’ve seen as many in 2026 as in 2025,” Sir Richard said. The RAF intercepts Russian jets approaching UK airspace, but no recent case of Russian military aircraft actually entering UK airspace, which extends 12 nautical miles from the coast.
The military chief also stressed the growing importance of drones and autonomous systems. “They are going to become increasingly important in the future of warfare,” he said, adding that the UK must invest more in that area.
Pressed on whether the government is willing to give the military the extra funding it says it needs, Sir Richard expressed confidence that ministers understand the threats and are increasing spending. “Exactly as the prime minister says, we need to spend more on defence and do it faster. The challenge for ministers is to make those difficult trade-off decisions,” he said.
The Defence Investment Plan, originally due in autumn 2025, has faced repeated delays — drawing criticism from MPs and former military leaders. Commons Defence Committee chairman Tan Dhesi said Britain’s military and defence industry “need to know where we stand and where we are going”. Former defence secretary Lord Robertson has criticised the UK’s diminished capabilities, while former chief of the defence staff Jock Stirrup warned the UK is “badly exposed”.
Sir Richard made clear the public must also understand the gravity of the situation. “It is important that society and all of us recognise and understand that, and that may mean that we need to make different choices and different priorities,” he said.