Saudi Arabia is pressing the U.K., Japan and Italy to be allowed to join a project for constructing a new, advanced fighter jet, the Financial Times reported.

Riyadh’s push to partner in the Global Combat Air Program is creating strains within the alliance, as the U.K. and Italy are open to the prospect while Japan is resistant, the FT said, citing officials it didn’t identify.

Crown Prince Mohammed bin Salman made a request to participate to Prime Minister Fumio Kishida when the pair met in Jeddah in July, the newspaper said.

Tokyo — which ended a decadeslong ban on arms exports in 2014 — is concerned that Saudi involvement could delay completion of the GCAP, which aims to build an advanced and exportable combat aircraft by 2035, the FT said.

Saudi Arabia could provide a significant financial contribution to the project, which is estimated to cost several billion dollars, and potentially offer some engineering assistance, according to the newspaper.