The UK government is poised to inject £6bn into the Global Combat Air Programme (GCAP), a joint stealth fighter project with Japan and Italy, according to three briefed individuals. This long-term funding aims to secure a multiyear industry contract covering design and development, replacing a short-term deal expiring next month.

Japan has intensified pressure, with Defence Minister Shinjirō Koizumi bluntly demanding a full contract without delay during recent talks. Officials warned Prime Minister Sanae Takaichi's planned UK visit next month could be cancelled if uncertainties persist, linking the programme's fate to broader UK-Japan strategic ties.

Over 4,000 UK staff already work on GCAP, which targets 2035 deployment to challenge US military tech dominance. The funding, expected alongside a wider defence settlement, will allow BAE Systems, Leonardo, and Mitsubishi Heavy Industries' joint venture to advance critical design work, directly impacting thousands of aerospace jobs and the UK's defence industrial base.