Japan is growing increasingly frustrated with UK delays to the Global Combat Air Programme, a joint fighter development effort with Italy. The £28 billion project faces setbacks after the UK postponed its 10-year defence investment plan, stalling crucial contracts with Edgewing, the commercial joint venture between the three nations' defence contractors.

Sources involved in the programme describe the situation as "terrible," with Japan's main goal of producing a new fighter by the mid-2030s potentially compromised. While Tokyo focuses on delivering a next-generation jet, London and Rome are more interested in developing a "system of systems" approach featuring drones working alongside the aircraft. This divergence in priorities has created tension among the partners.

The delays come at a precarious time for global security, with rising tensions in the Middle East and an unpredictable US administration under Donald Trump. Japan has begun exploring potential new customers like Canada to reduce reliance on UK funding, though officials remain reluctant to bring in additional development partners. The UK Ministry of Defence maintains the collaboration remains strong, citing the opening of the trilateral GCAP headquarters in Reading and ongoing engineering work by BAE Systems, Leonardo, and Mitsubishi Heavy Industries.