Why the Defence Secretary Resigned Over Defence Spending

John Healey resigned from the Cabinet on 16 June 2026, telling Prime Minister Keir Starmer that the government's defence spending plan was "well short of what is required." He was the Defence Secretary — one of the most senior jobs in government — and his departure marks the biggest ministerial row over defence money in years.

The row has been building since the Strategic Defence Review was published in July 2025. That review sets out what Britain's military needs to do and what it will cost. Healey wrote in his resignation statement that Britain's enemies "don't follow timetables set by the Treasury" — a way of saying the issue is not just about numbers, but about real security risks. The armed forces' top commanders have put an exact figure on that risk: they say there is a £28 billion shortfall in defence funding over the next four years. They told Starmer directly.

The money gap

No one disagrees about how big the problem is. UK defence spending as a share of GDP is forecast to rise from 2.60 to just 2.68 per cent between 2026 and 2030 — that is, defence spending is not growing as fast as the overall economy. This leaves the UK below NATO's informal target of 3 per cent and, more importantly, below what the Ministry of Defence itself says it needs to spend.

The Defence Ministry's annual report, published in November 2025, described the period ahead as "a new era of threat requiring a new era for UK defence." The Treasury is offering less money than that language suggests is necessary. That gap is where the crisis began.

Reports from 16 June show that when the Defence and International Policy plan is finalised — it is late — the armed forces look set to face cuts. They will have to spend less on buying new equipment and on running their current operations. A BBC report the same day said military chiefs warned that training and operations will have to be "dialled back" without more cash. For forces already stretched across NATO's eastern border, the Indo-Pacific region, and security at home, that is a real problem, not a theoretical one.

What else is at stake

The warnings have come from outside government too. A former NATO chief wrote in April 2026 that Starmer was not doing enough to address Britain's security, and that significant new spending would be needed. A former senior military officer told Reuters in June 2026 that low defence budgets are scaring away private investors and pushing defence companies to move overseas. This matters because when defence companies leave, it takes years — sometimes decades — to rebuild the British manufacturing capacity to replace them.

The government has tried to find extra money. In February 2025, it cut the international aid budget to pay for more defence spending. Charities complained this would hurt the UK's influence overseas, and it stirred its own political row. Even so, that switch has not closed the gap that military leaders and Healey say is necessary.

The Defence Equipment and Support annual report did confirm one piece of progress: a counter-intelligence team for the defence industry has been fully operational since March 2024. It helps spot threats to defence manufacturing. But that does not address the main problem — the shortage of money.

What happens now

Healey's resignation means Starmer must choose a new Defence Secretary while the spending plan is still unsettled. NATO allies are watching closely. The new Defence Secretary will inherit a department whose military leaders have said publicly that they cannot do the job on the money they are getting right now. The Strategic Defence Review commits the UK to do things that the Treasury's current offer does not fund. And Healey's resignation letter is now public.

The Treasury has not changed its position as of 17 June 2026. Until it does, the central problem of British defence policy — and the central political problem for this government — remains the same: a gap between what the defence review promises and what the money will deliver.