Britain's Defence Secretary John Healey arrives at Downing Street to attend a cabinet meeting in central London, May 12. Healey resigned, in a surprise move which he said was due to Prime Minister Keir Starmer and his finance ministry failing to commit sufficient resources to long-term defense plans. AFP-Yonhap

LONDON — British Defense Minister John Healey quit on Thursday in a dispute over military spending, accusing Prime Minister Keir Starmerof failing to commit the government resources that are needed to defend the country at a time of heightened threat.

The unexpected resignation, accompanied with a scathing public letter, compounds the pressure on Starmer when he is facing a likely leadership challenge and exposes the crisis at the heart of government — how it can ramp up defense spending when there is no money to spare.

Britain's defense and finance ministries have been locked in talks for months over how to meet rising demands to expand military spending, delaying Britain's Defense Investment Plan which was expected to be published last year.

Military leaders have stressed the plan is needed to meet the rising threat level at a time of frequent Russian incursions into British waters, but the government is already struggling to reduce debt while the overall tax burden at its highest level in decades.