The United Kingdom is preparing to commit approximately £6 billion toward the development of a next-generation stealth fighter jet as part of the Global Combat Air Programme (GCAP), a collaborative effort with Japan and Italy. This funding boost aims to secure a multiyear contract with industry partners to advance the project’s design and development phase, sources familiar with the matter said. The move comes as the current short-term funding arrangement, which was announced in March, is set to expire at the end of next month.

The planned investment signals a significant step forward for the GCAP, which seeks to produce a new generation of stealth combat aircraft capable of deployment by 2035. The programme represents a strategic collaboration between the three nations to develop cutting-edge military aviation technology and serve as a counterbalance to U.S. dominance in the field. An international treaty underpinning the project was signed by the partners in December 2023.

Delays in finalizing a long-term contract have been attributed to the postponement of the UK’s Defence Investment Plan, the country’s decade-long military strategy. The absence of firm financial commitment has drawn criticism, particularly from Japan, where officials have expressed concern over the programme’s future amid broader uncertainties surrounding UK defence spending. Tokyo’s unease was reportedly conveyed during recent discussions involving Home Secretary Yvette Cooper and Japan’s Defence Minister Shinjiro Koizumi, who emphasized the need for the UK to commit to a full, multiyear contract without further postponements.

There are also reports that Japan is reconsidering the planned visit of Prime Minister Sanae Takaichi to the UK next month, underscoring the risk that political instability within the UK, including ongoing leadership questions surrounding Prime Minister Sir Keir Starmer, could undermine the collaboration. Japan’s concerns highlight the strategic importance of the project not only for its military outcomes but also for the bilateral relationship and the partners’ positioning in the Asia-Pacific region.

The GCAP industrial partnership involves BAE Systems from the UK, Leonardo from Italy, and Japan Aircraft Industrial Enhancement, a Mitsubishi Heavy Industries-backed consortium. More than 4,000 workers in the UK alone are engaged on the project, including efforts on a demonstrator aircraft designed to validate key technologies for the GCAP fighter jet.

While the Treasury and Edgewing, the joint venture handling much of the programme’s development, did not comment on the funding plans, the UK Ministry of Defence reiterated its dedication to the project. A spokesperson confirmed the government’s commitment to working closely with Italy and Japan to finalize the international contract and move forward with the next phases of the programme.

The forthcoming funding agreement is expected to be announced alongside a broader defence spending settlement, though it remains subject to final Treasury approval. The outcome of this decision will have far-reaching implications for the future of the GCAP and the strategic defence relationships between the three partner nations.