Downing Street published an exchange of letters on 11 June 2026 showing that John Healey had resigned as Defence Secretary and that Sir Keir Starmer had accepted his departure the same day. The correspondence turns a budget dispute into a formal public record, with both men setting out different views on whether the Government’s Defence Investment Plan is sufficient for the current threat environment and for the programme set by the Strategic Defence Review. (gov.uk) Healey’s position is clear. He says the plan offered to the Ministry of Defence does not provide the resources needed now, while Starmer’s reply says any further increase must be funded through sustainable reallocations across government rather than looser borrowing. Read together, the letters point to a Cabinet-level dispute over the pace and certainty of defence funding, not over the principle of spending more on defence. (assets.publishing.service.gov.uk)
Healey uses his resignation letter to argue that the department has already moved quickly since Labour entered office in July 2024. He points to work on Ukraine through the Coalition of the Willing and the Ukraine Defence Contact Group, a stronger UK role in NATO, a rise in defence investment, publication of the Strategic Defence Review, major reform work, a substantial pay rise for service personnel, action on forces housing, and new defence agreements with Germany, Norway and France. The Strategic Defence Review itself was commissioned in July 2024 and published in June 2025 as the Government’s long-term plan for reshaping UK defence. (assets.publishing.service.gov.uk) That context matters because Healey is not presenting the resignation as a break with the wider defence agenda. His letter instead argues that the agenda already agreed by government now requires a faster funding profile if it is to be carried through in full. In policy terms, the dispute is about delivery capacity rather than overall direction. (assets.publishing.service.gov.uk)
The central complaint is about timing and scale. Healey says cross-government work completed in January 2026, overseen by the Prime Minister, the Chancellor and the Defence Secretary, had already confirmed the scale of the defence challenge. He says the final settlement shown to him in full that week remained backloaded, reaching only 2.68% of GDP in 2030, even though the Government’s wider spending plans already point to 2.6% from 2027. He argues that Britain should instead set a firmer milestone of 3% of GDP on defence in 2030. (assets.publishing.service.gov.uk) Healey links that funding profile directly to operational risk. He cites current and expected demands in the Middle East, the High North and Ukraine, and says a plan that leaves pressure concentrated in the first two years would force decisions that reduce readiness and increase risk to personnel on operations. In plain English, his case is that the Ministry of Defence cannot meet present commitments and the Strategic Defence Review timetable unless money arrives earlier and in greater volume. (assets.publishing.service.gov.uk)
Starmer’s reply accepts the broad security diagnosis but rejects Healey’s conclusion on what can be afforded. The Prime Minister says the Government has already delivered the highest sustained increase in defence spending since the Cold War, including through a reduction in the aid budget after taking office in 2024, and says the Defence Investment Plan will provide resources for the military, planning certainty for industry and support for jobs and growth in Britain. (assets.publishing.service.gov.uk) The Prime Minister also frames the argument as one of fiscal method. His letter says the increases behind the plan will be "sustainable and fair", will require significant reallocations from other departments and must not depend on what he describes as irresponsible borrowing. That places Treasury discipline, rather than departmental demand, at the centre of the final settlement. (assets.publishing.service.gov.uk)
The administrative effect is significant because the Defence Secretary’s brief extends well beyond political messaging. GOV.UK states that the post carries responsibility for the defence budget, resource allocation, implementation of the Strategic Defence Review and Defence Investment Plan, operational oversight, and membership of the National Security Council. A resignation at the moment the investment plan is being settled therefore interrupts ministerial ownership of the department’s most important spending and reform decisions. (gov.uk) That does not mean the policy framework disappears. The Strategic Defence Review remains published government policy, and Spending Review 2025 already set the broader path to 2.6% of GDP from 2027, with an ambition to reach 3% in the next Parliament when economic and fiscal conditions allow. What changes immediately is who carries the political authority to translate that framework into procurement, readiness and force-structure choices inside the Ministry of Defence. (gov.uk)
Politically, the exchange matters because it exposes a precise fault line inside government. Healey is not arguing against higher defence spending over time; he is arguing that the pace now chosen is too slow for the threat assessment and for the commitments the UK has already made. That is consistent with his call for a 3% milestone in 2030 and with his reference to the UK-backed NATO path to 3.5% of GDP on core defence by 2035. (assets.publishing.service.gov.uk) Starmer’s position is different. Spending Review 2025 presents 2.6% from 2027 as the settled path and 3% only as an ambition for the next Parliament if conditions permit. Read against that published position, the letters show a disagreement over whether defence should receive a faster and more firmly dated uplift than the Treasury is prepared to underwrite. (gov.uk)
For the department, the immediate test is continuity. The Ministry of Defence is in the middle of implementing the Strategic Defence Review, reshaping procurement, housing, technology and industrial policy, while also supporting ongoing missions linked to Ukraine, the Gulf and the High North. Publication of the letters does not reverse those commitments, but it does signal that the next phase will be managed under close scrutiny over cost, timing and cross-government trade-offs. (gov.uk) The correspondence also provides a detailed public record of the disagreement. Rather than a generic resignation statement, Downing Street has published both sides of the case, making clear that the issue is whether the Defence Investment Plan matches the Government’s own threat assessment and stated defence ambitions. For officials, industry and Parliament, that is the main practical point: the strategic direction remains in place, but the funding timetable behind it is contested at the top of government. (gov.uk)