The Treasury is preparing to seize control from the Ministry of Defence over spending on the £15bn military funding injection, including £6bn for the Global Combat Air Programme (GCAP). The move comes as the government finalizes its 10-year Defence Investment Plan, with Prime Minister Sir Keir Starmer set to announce the settlement soon.

Chancellor Rachel Reeves fears the GCAP is "just the next HS2," referring to the beleaguered high-speed rail project. One official described the MoD's attitude toward taxpayer money as "delinquent." The Treasury cites the ministry's dismal record of cost overruns on major military projects as justification for taking control of the UK-Italy-Japan stealth fighter program.

Japan has expressed alarm over funding uncertainty as its Prime Minister Sanae Takaichi visits Britain next week. The GCAP faces a £28bn funding gap over the next four years, with delivery potentially slipping beyond the 2035 service date established by the three nations. The interim funding deal expires at the end of June.