Britain's top military chiefs held a "very difficult" meeting this week over how to fund plans to rebuild the armed forces amid fears of further cuts, defence sources have said.
The Ministry of Defence (MoD) played down a report in the Spectator magazine that the top brass, led by Air Chief Marshal Sir Rich Knighton, the chief of the defence staff, planned to write an extraordinary joint letter to John Healey, the defence secretary, to explain that his defence review published in June cannot be delivered without more cash.
"There is not a letter," an MoD source said, adding that such a communication was not expected to be received either.
However, other sources from within the army, navy and air force confirmed to Sky News there is growing concern among the chiefs about a gap between the promises being made by Sir Keir Starmer's government to fix the UK's hollowed-out armed forces and the reality of the size of the defence budget, which is currently not seen as growing fast enough.
That means either billions of additional pounds must be found more quickly, or ambitions to modernise the armed forces might need to be curbed despite warnings of mounting threats from Russia and China and pressure from Donald Trump on the UK and the rest of Europe to spend more on their own defences.
"The facts remain that the SDR (Strategic Defence Review) shot for the stars, but we only have fuel for the moon," one source said.
A second source agreed.
By way of example, they said General Sir Roly Walker, the head of the army, was all too aware of the financial challenges his service in particular was facing, especially given plans to regrow the force to 76,000 soldiers from 72,500 in the next parliament.
The defence review set out the requirement for more troops, but such a move would need sufficient money to recruit, train and equip them.
There is also a goal to expand reserve forces, which similarly costs money.
Air Chief Marshal Knighton and General Walker were joined in the meeting on Tuesday at the Ministry of Defence by the other service heads, General Sir Gwyn Jenkins, the First Sea Lord, and Air Chief Marshal Harv Smyth, the Chief of the Air Staff.
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General Sir Jim Hockenhull, the commander of Cyber and Special Operations Command, was also likely to have been present.
It is a regular fortnightly gathering of chiefs.
This week they discussed the content of an upcoming plan on defence investment that is expected to be published next month - a timeline that is understood to have been delayed because of friction over how to make the money match the ambition.
"I know there was a very difficult meeting," a third source said.
"Shoehorning the SDR into the DIP (Defence Investment Plan) as inflation, foreign exchange movement, re-costing, in-year delivery drama and unforeseen additional costs arise was always going to be hard," the source said.
"The amount of money needed to make the thing balance is both small compared to other parts of the public sector, but also not available from this government. It's still a matter of choices, not overall affordability."
The source pointed to what Germany and Poland are doing on defence, with both countries significantly and rapidly ramping up defence spending and expanding their militaries.
By contrast, the UK will only inch up its core defence budget to 2.5% of GDP from around 2.3% by 2027, with plans to hit a new NATO target of 3.5% not expected to be reached until 2035.
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Responding to the Spectator claim, an MOD spokesperson said: "All of defence is firmly behind delivery of our transformative Strategic Defence Review (SDR), which set out a deliverable and affordable plan to meet the challenges, threats, and opportunities of the 21st century.
"The plan is backed by the largest sustained increase in defence spending since the end of the Cold War - hitting 2.6% of GDP by 2027."
The 2.6% figure cited by the spokesperson also includes intelligence spending on top of core defence spending.
(c) Sky News 2025: Military chiefs in 'difficult meeting' as tensions mount over money

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