John Healey, Britain's defence secretary, resigned on Thursday in a furious dispute with Keir Starmer over military spending, accusing the prime minister of failing to provide the resources needed to protect the country at a dangerous moment. His scathing resignation letter, which warned that the government's long-delayed Defence Investment Plan ‘falls well short of what is required’, marks the sixth ministerial departure in a month and plunges Starmer's already weakened administration into fresh turmoil. Healey, a Labour loyalist of three decades, was seen as a steady hand at the Ministry of Defence; his exit over a budgetary clash with the Treasury demolishes that image and leaves No 10 reeling just weeks before a high-stakes NATO summit in which US president Donald Trump is expected to demand higher European defence contributions.

At the heart of the rupture lies the government's inability to reconcile ambitious rhetoric on security with fiscal reality. Healey had pressed for a pathway to 3% of GDP in defence spending, yet the plan Starmer presented forecasts only 2.6% next year and 2.68% by 2030, with a 3% target pushed to 2034–35. The departing minister pointed to intensifying threats — Russian aggression in Ukraine, Iran's destabilising activities, and the UK's leading role in the Strait of Hormuz maritime mission — to argue that delay imperils the nation. Hours later, armed forces minister Al Carns, a decorated veteran, also quit, telling the prime minister that No 10 ‘refuses to listen’ and that current investment levels are ‘inadequate’. The twin resignations expose a deep rift within the defence establishment and feed the perception that Starmer's government is incapable of translating its security pledges into action.

Starmer moved swiftly to stem the crisis, naming Dan Jarvis as Healey's successor. The 53-year-old former paratrooper and security minister in the Home Office is a close ally of the prime minister and brings serious military credentials to the role: a graduate of Sandhurst and the Royal Military Academy, he served in the Parachute Regiment and later studied at Aberystwyth. The appointment was welcomed in some quarters, though Russian media seized on Jarvis's past remarks about readmitting Moscow to the G7, a detail that will draw scrutiny in allied capitals. Jarvis inherits a ministry in revolt, where morale has been battered by a perception that the Treasury, not strategic necessity, writes defence policy.

Viewed from Washington, the upheaval complicates transatlantic coordination at a delicate juncture. Trump has leaned heavily on NATO partners to shoulder a greater share of the burden, and Britain's internal wrangling over a few tenths of a percent of GDP undercuts Starmer's efforts to position himself as the linchpin of the European ‘coalition of the willing’ supporting Ukraine. In Europe, diplomats worry that a protracted leadership crisis in London will hobble joint planning on everything from procurement to the next iteration of the AUKUS pact. Analysts in London note that the resignations strip away any pretence of cabinet unity and may embolden Labour rebels who have been quietly manoeuvring against Starmer.

Looking ahead, the new defence secretary must quickly produce a credible investment plan that satisfies both the armed forces and a sceptical Treasury, while reaffirming Britain's commitments to allies. Starmer's political survival now hinges on his ability to restore order and demonstrate that his government can deliver on the core duty of national defence. The upcoming NATO summit, at which Trump is expected to amplify his demands, will offer an unforgiving stage on which to prove it. For now, the prime minister presides over a party fraying at the seams, with a key department in chaos and the nation's security debate mired in acrimony rather than strategy.