Japan, the U.K. and Italy are close to announcing a political agreement on a new jet fighter, joining forces to fund a multi-billion dollar program capable of competing with the next generation of warplanes from the U.S. and elsewhere.

The accord on the project, to be called the Global Combat Air Program, is expected next week, according to people familiar with the issue. Parties involved had said in July, when Japan’s likely involvement was announced, that the aim was to seal an agreement by year-end. The date could slip to later in the month, one of the people said.

Britain and Italy have been developing the Tempest warplane to rival France and Germany’s so-called Future Combat Air System plane for some years. London and Rome have been working on bringing Japan into the group, with Sweden another prospective partner.