Britain's Defence Secretary, John Healey, has resigned from the government, citing concerns that planned defence spending falls short of what is needed to address mounting security threats and maintain military readiness.

In a resignation letter dated June 11, 2026, and addressed to Prime Minister Keir Starmer, Healey said he could no longer support the government's Defence Investment Plan (DIP), arguing that it failed to provide the resources required to meet growing defence commitments at home and abroad.

“This is a letter I never expected to write, and I do so now with great regret and reluctance,” Healey wrote.

Defence Spending at Heart of Resignation

Healey said he had advocated for a target of spending 3% of gross domestic product (GDP) on defence by 2030, describing it as a necessary benchmark amid what he characterized as a worsening security environment.

According to the letter, the government's current funding settlement would increase defence spending to 2.68% of GDP by 2030, a level Healey argued was insufficient to meet operational demands and future threats.

“As we have regularly discussed, I am certain that a headmark date for 3% of GDP on defence in 2030 is what Britain must set,” he wrote.

Healey said the gap between defence requirements and available funding had left him facing decisions that could reduce military readiness, increase risks to personnel and weaken national security.

“Without a DIP that meets the moment in this way, I am being forced to make decisions that would reduce the readiness of our Forces and increase the risk to personnel on operations,” he said.

Cites Rising Global Threats

The outgoing defence secretary pointed to a range of security challenges facing the United Kingdom, including continued Russian military activity, the war in Ukraine, instability in the Middle East and Britain's expanding commitments to NATO allies.

He referenced Britain's leadership roles in multinational operations, including missions related to the Strait of Hormuz and NATO's Arctic security efforts, arguing that defence demands had increased significantly since the government took office.

Healey also cited assessments from NATO partners warning that Russia could pose a direct threat to the alliance as early as 2030.

“You spelled out the threats last week: ‘it is our intelligence assessment, and the assessment of other countries in NATO, that there could be an attack by Russia on NATO as soon as 2030,’” he wrote to Starmer.

Praises Government Achievements

Despite his criticism of defence funding plans, Healey praised the Labour government's broader record and expressed support for the prime minister.

He highlighted increased military spending, defence reforms, support for Ukraine, NATO cooperation and efforts to improve conditions for armed forces personnel.

“I am proud of what we have done in less than two years as a Labour Government,” he wrote.

Healey also thanked Starmer for his leadership and said he remained committed to supporting the government from outside the cabinet.

“I wish you all continuing strength in the exceptional challenges you face as Prime Minister. As always, our Labour Government will continue to have my fullest support,” he wrote.

Defence Investment Dispute

The resignation follows an apparent disagreement between the Defence Ministry and the Treasury over long-term military spending commitments.

Healey said discussions on a Defence Investment Plan had sought both to address immediate operational pressures and establish a pathway toward a NATO spending commitment of 3.5% of GDP by 2035.

However, he argued that the government had been unwilling to commit the resources necessary to achieve those goals.

“After explaining to you that I would not be able to accept a DIP settlement that does not give our Forces the resources they need, I am now left with no other option than to submit my resignation as your Defence Secretary,” he wrote.

The Prime Minister's Office had not immediately commented on the resignation.