British Prime Minister Keir Starmer says he will fight to remain in office after the sudden resignation of his defense secretary, which he said has undermined his authority. Multiple outlets report that Starmer frames the departure as a serious political challenge and portrays his response as determined and ongoing, rather than stepping down. The resignation comes amid a major defense policy effort: the government’s long-awaited Defense Investment Plan, described as a roadmap for increasing military spending. According to one report, the plan sets out a target of raising defense expenditure to 3.5% of GDP by 2035. While the articles agree on the core events—the defense minister’s sudden departure and Starmer’s vow to stay—details about the resignation’s specific reasons are not provided in the supplied excerpts. Overall, the coverage emphasizes the immediate political fallout for Starmer’s leadership and the relevance of the defense spending plan to the government’s longer-term agenda.