In a highly unusual intervention, the Chief of the Defence Staff, Air Chief Marshal Sir Richard Knighton, has written personally to Prime Minister Keir Starmer to warn that the government’s proposed defence investment plans are inadequate and fall well short of what is needed to prepare Britain’s armed forces for modern high-intensity conflict.
The letter was sent ahead of a long-awaited announcement on the Defence Investment Plan (DIP), which has been repeatedly delayed amid bitter battles between the Ministry of Defence and the Treasury.
The Chief of the Defence Staff told the BBC “This is the most dangerous period that I have known”, with the threats being greater now than at any time since the Cold War.
He stressed the need for the military to prepare to fight longer wars, as in Ukraine, while it has spent recent times preparing for short, contained conflicts.
Senior military sources describe the current funding offer — understood to be around an extra £13 billion — as “underwhelming” given the scale of the challenge.
British media reports that the PM was pushing for £18 billion
Military chiefs have warned that the MoD faces a £28 billion shortfall over the next four years simply to meet existing commitments and move towards genuine “warfighting readiness”, as set out in last year’s Strategic Defence Review.
The plan was originally due in autumn 2025 but has been pushed back multiple times.
Although they have not specified a date, ministers have promised to reveal the plans before to the NATO meeting in Turkey on July 7.
Sir Richard’s decision to put his concerns in writing to the Prime Minister is rare for a serving Chief of the Defence Staff and signals deep frustration within the armed forces over the government’s pace and level of ambition on defence.
The intervention comes as the UK prepares for the upcoming NATO summit and faces growing pressure to demonstrate it is serious about rearmament amid heightened threats from Russia, China and others.
Senior opposition figures have accused the Starmer government of dangerously dithering at a critical moment, leaving Britain’s military hollowed out after years of under-investment.
A government source said the Prime Minister remains committed to raising defence spending, but no final figure has yet been agreed. The Defence Investment Plan is now expected to be published in the coming days.
Currently, the UK spends 2.3 per cent of its GDP on defence and even with the proposed increases, progress remains slow and heavily back-loaded.
Yet the government does not plan to reach the new NATO target of 3.5 per cent of GDP on core defence spending until 2035 — the furthest possible deadline set by allies.
The Royal Navy currently has zero attack submarines available for operations, with all five of its Astute-class hunter-killer boats docked for maintenance or technical issues.https://t.co/meN43MLX81
— Brussels Signal (@brusselssignal) June 8, 2026
