Britain’s top military officer has warned that the UK faces its most dangerous period since the Cold War, with Russia probing and challenging defences in a way that risks crossing a line. Chief of the Defence Staff Sir Richard Knighton told the BBC that the threats to the country are greater now than at any time in his working life. His remarks come as the government’s long-awaited Defence Investment Plan (DIP) – intended to set out how new equipment and infrastructure will be funded over the next decade – has faced repeated delays, drawing criticism from MPs and former defence secretaries.
At its core, the situation is about the UK’s ability to respond to a resurgent Russia while adapting to modern warfare. Sir Richard said Russia has been “probing, challenging, testing our defences” with long-range aviation flights that approach UK airspace. He noted that in 2026, the number of such flights matched the level seen in 2025 – a sign that Moscow is “raising the stakes”. Although Russian military aircraft have not entered UK airspace (which extends 12 nautical miles from the coast), the activity in the High North, including the Arctic, has intensified. Meanwhile, the nature of conflict is changing: drones and autonomous systems are becoming “increasingly important in the future of warfare”, Sir Richard said, and the UK must prepare for longer wars like the one in Ukraine, rather than the short, contained conflicts the armed forces have focused on in recent decades.
“Britain's top military chief warns of greatest threat since Cold War; DIP delays criticised.”
The background to this warning stretches back to the end of the Cold War, when defence budgets were cut and the UK’s military posture shifted away from large-scale territorial defence. Russia’s 2022 full-scale invasion of Ukraine shattered the assumption that major state-on-state war in Europe was unthinkable. The government’s response was the Strategic Defence Review, published in 2025, which was described as a “call to arms”. The DIP – the financial blueprint to implement that review – was supposed to follow in autumn 2025 but was repeatedly delayed. On Friday, Prime Minister Sir Keir Starmer said it would be published “in just a few weeks’ time” before a Nato summit beginning on 7 July. However, the Public Accounts Committee (PAC) has been scathing. Its chair, Sir Geoffrey Clifton-Brown, said the delay has damaged Britain’s safety, emboldened its enemies, and that ministers should apologise. He added that the Ministry of Defence has yet to decide which capabilities, infrastructure and people it needs within the available budget. Former Labour defence secretary Lord Robertson accused the government of “corrosive complacency” and said “non-military experts in the Treasury” had committed “vandalism”.
For UK readers, the immediate impact is on national security and public spending. The military says it needs more money spent faster to counter Russian threats, but the Treasury faces difficult trade-offs. The delay in the DIP has created uncertainty for the armed forces and the defence industry, which relies on long-term contracts. MPs also warn that the delay signals weakness to allies and adversaries. On a practical level, the RAF continues to intercept Russian aircraft approaching UK airspace, and the government has pledged that protecting the UK is its “top priority”. But until the DIP is published, there is no firm plan for how the military will modernise – including investing in drones and autonomous systems – or how it will maintain readiness for a prolonged conflict.
Q: What is the Defence Investment Plan (DIP)? The DIP is a government document that will set out how the UK plans to fund new military equipment, infrastructure and personnel over the next ten years. It is meant to implement the recommendations of the 2025 Strategic Defence Review.
Q: Why is Britain’s military worried about Russia? Russia has been increasing long-range aviation flights near UK airspace, probing defences and testing response times. Sir Richard Knighton described this as the most dangerous period since the Cold War, with Russia “raising the stakes” and risking crossing a line.
Q: What are the UK’s current defence capabilities? The UK armed forces have been focused on short, contained conflicts in recent decades. The military chief says the UK now needs to prepare for longer wars like Ukraine’s, and that drones and autonomous systems will be crucial. However, specific capabilities have not been fully decided due to the delay in the DIP.
What happens next is tied to the publication of the Defence Investment Plan, which the prime minister has promised before the Nato summit in July. Once released, it will reveal the government’s spending priorities and whether the military’s demands for faster, higher spending are met. Meanwhile, Russia’s probing is likely to continue, and the UK’s allies will be watching closely for signs that Britain is serious about its defence commitments.