Japan, Italy and the United Kingdom have unveiled a new conceptual design of the next-generation fighter jet they plan to develop together, amid growing speculation that a new British defense review could impact the future of the multibillion-dollar project.

A full-scale model of the new design was jointly showcased Monday by Japan’s Mitsubishi Heavy Industries (MHI), Italy’s Leonardo and Britain’s BAE Systems — the project’s lead system integrators — at the Farnborough International Airshow near London.

While unlikely to be the final design, the refined concept features major changes in the wing and aft fuselage areas, ostensibly meant to improve the aerodynamics of the future twin-engine, sixth-generation fighter.