John Healey resigned as Defence Secretary in June 2024 after disagreeing with Prime Minister Keir Starmer over how much and how quickly the government should increase military spending, the BBC reported.

In his resignation speech to the House of Commons on 16 June 2024, Healey said the government's defence spending plans "fall well short" of what is required. The Treasury's proposed budget would raise defence spending to 2.68% of GDP — the value of all economic output in the UK — according to PBS NewsHour. But Healey had previously promised, while in post, to reach 5% of GDP by 2035. Labour had marketed this target as the largest sustained boost to core defence funding since the Cold War ended.

The gap between 2.68% and 5% sits at the heart of the dispute. The Treasury's trajectory meets neither the 2.5% halfway target that Healey himself once called "fully funded" and praised, nor the 5% end-point he had championed publicly. His Commons speech drew a direct line between his own stated targets and the government's failure to meet them.

Background: from ambition to resignation

Healey's time in the job involved a series of escalating spending pledges. The Spring Statement 2025 added £2.2 billion to the Ministry of Defence budget for 2025/26. Later that year, he announced a £5 billion boost and, at the September 2025 NATO defence spending debate, pointed to agreement among all 32 NATO alliance members to raise defence spending. The government claimed this package represented the largest increase in defence funding since the Cold War.

This message was central to how Labour positioned itself on national security. The party's campaign materials describe a commitment to 5% of GDP by 2035, and Healey repeated that promise at Labour Party Conference 2025. What the resignation reveals is that the Treasury never fully committed to that target in actual budget allocations — and when the numbers were tested in detailed discussions, they fell apart.

What happens next

Healey's departure removes Starmer's most prominent defence voice at a moment when NATO allies are scrutinising how much each country contributes. The 5% target — once Labour's political selling point on security — now sits uncomfortably in the public eye: mentioned in party materials and endorsed at conference, but apparently unsupported by Treasury spending plans.

For those watching Westminster closely, the question is whether his successor will inherit the 5% commitment or quietly drop it. The 2.68% trajectory is not trivial — it would exceed NATO's longstanding minimum of 2% — but it falls well short of what Healey was publicly calling for, and well short of what several European allies are planning.

Defence spending is a reserved matter, controlled entirely at Westminster. That means the dispute has direct effects across all four nations of the UK: no devolved government has any say here. The only way the spending targets change is through negotiation between the Treasury and the Ministry of Defence.

When cabinet ministers resign over spending rather than scandal or policy shifts, the political consequences tend to be longer-lasting. They set a public standard by which their successor's deals will be judged. Healey has now set that standard himself, on the record in parliament.