The head of Britain’s military has said that the threats to the UK are greater now than at any time since the Cold War.

Sir Richard Knighton’s warning comes as Vladimir Putin ramps up his threats against Britain, with Russian jets entering British airspace as many times in the first five months of 2026 as they did throughout the entirety of last year. 

The military chief said that Russia risks ‘crossing a line’ and described last year’s Strategic Defence Review as a ‘call to arms’ urging the UK’s armed forces to switch focus from short conflicts to longer wars such as in Ukraine. 

His intervention comes ahead of the publication of the Defence Investment Plan which is expected to be published before a NATO summit on July 7 following repeated delays. 

The document will set out how new equipment and defence infrastructure will be funded over the coming decade.

It follows a Strategic Defence Review from former NATO chief Lord Robertson in June last year which called for a greater investment in the armed forces.  

Speaking to Radio 4’s Today Programme, Sir Richard said that threat from Moscow was impacting the whole of Europe with NATO forces being scrambled 700 times in response to Russian activity. 

Just last week, a Russian drone hit a block of flats in Romania causing a fire and injuring two people.

Sir Richard Knighton – the head of Britain’s military – (pictured) has warned the threats to the UK are greater now than at any time since the Cold War

A Russian Su-27 aircraft. Sir Richard Knighton warned that Russian jets have entered British airspace as many times in the first five months of 2026 as they did throughout the entirety of last year

In April, British fighter jets were scrambled towards the Shetland Islands following reports of an unidentified Russian warplane flying outside British airspace. 

He said: ‘We’re seeing Russia probing, challenging and testing our defences, both traditional and through cyber attacks, trying to smuggle technology, and carrying out reckless sabotage and assassination attempts.’

‘So Russia is raising the stakes and risks crossing a line.’

In a daunting admission, Sir Richard added that the threats to Britain and its allies are now so high that it is the most dangerous period of his 35 year career.

He continued: ‘As a consequence it is important we enhance the capability of our armed forces alongside our allies to deter adversaries from doing something daft.

‘The Strategic Defence Review set out clearly that the armed forces we have today have been shaped by the world we faced over the last 25 years but the world is changing and what is expected of defence is changing and we’re expected to do different things as a consequence of that changing environment.’ 

Sir Richard also said that drones and other autonomous systems are becoming ‘increasingly important in the future of warfare’, urging for more investment in the field.

Drones have played a crucial part in the Ukraine war. Earlier this week, Kyiv carried out a daring drone attack on the outskirts of St Petersburg mere hours before a major economic forum in the Russian city designed to attract foreign investors.

Pictured: A  block of flats on fire in Romania following a Russian drone strike last week 

A British Typhoon FGR4 fighter jet. One of the jets set off over the coast of Scotland to intercept a Russian warplane in April 

Echoing Lord Robertson’s previous claim that Britain’s national security could be left ‘in peril’ if defence spending is not increased, Sir Richard said the government needs to ‘spend more and do it fast’.

He said: ‘The Government has committed to spend more on defence as the Prime Minister says we need to spend more and do it faster. The challenge for ministers is to make those difficult trade-offs and I’m confident the Prime Minister and ministers understand the threats.

‘Lord Robertson is right that the world is changing and we need to enhance capability as the threat from potential adversaries grows.’ 

It previously emerged that the MoD is facing a £28billion shortfall between now and 2030, with the Prime Minister said to have been given the dire financial assessment before Christmas.

James Cartlidge, the shadow defence secretary, said it was ‘extraordinary’ that military chiefs are being asked to find cuts at a time of ‘war on two fronts’ in the Middle East and Ukraine.

The senior Tory MP pointed to how Labour had spent around £3billion on lifting the two-child benefit cap, adding: ‘Politics is always about what you prioritise.’

Recent polling has found that Brits are split on whether to increase defence spending with many members of the public resistant to the trade-offs and cuts that might follow such an increase.

Ipsos found that 37 per cent of Britons say government spending on defence and the Armed Forces should be increased, even if this means extra Government borrowing, higher taxes, or less money to spend on other public services. 

Recent polling has found that Brits are split on whether to increase defence spending with many members of the public resistant to the trade-offs and cuts that might follow such an increase

Meanwhile, 40 per cent think defence spending should remain the same and 15 per cent believe defence spending should be decreased.   

Around half of Brits would oppose an increase in defence spending if it meant a decrease in spending on public services or tax rises.  

Commenting on the findings, Caroline Paskell, Research Director at Ipsos in the UK, said: ‘Our latest polling underscores the public’s anxiety about the financial realities of funding Britain’s armed forces, showing that while there is an in-principle desire for a strong military, it is not immune from the intense competing pressures facing other public services. 

‘For instance, since the peak in March this year there has been a measurable softening in the proportion of the British public who want to see military funding grow, although it remains higher than in 2022.’