The leaders of Japan, Britain and Italy have discussed the possibility of bringing more nations into their joint fighter aircraft development program while reiterating their “unwavering commitment” to seeing the next-generation supersonic jet take to the sky by 2035.

The three partners talked about their “ambition to widen participation to a broader range of international partners in future,” said British Prime Minister Keir Starmer, following a meeting with his Japanese and Italian counterpartners, Shigeru Ishiba and Giorgia Meloni, on Tuesday on the sidelines of a Group of 20 summit in Brazil.

No further details were provided, including on which additional partners are being considered or what their exact role or contribution to the multibillion dollar Global Combat Air Program (GCAP) would be.

Saudi Arabia is among the countries reported to have shown interest in joining the multilateral endeavor.

In a separate statement, Ishiba did not address the possibility of expanding the three-way partnership but highlighted the importance of GCAP as “the cornerstone of broad cooperation among the three countries for decades to come.”

The gathering in Rio de Janeiro came about a week after Italy joined Japan and Britain in ratifying the GCAP treaty, which not only binds the three countries to the program by law, but also formally establishes the GCAP International Government Organization (GIGO), which will set out the aircraft’s overall capability requirements while overseeing the associated industrial constructs.

Moreover, the move also enables GCAP, which is seen as a basis for enhancing each country’s defense-industrial base, to officially move on to the next stage — the aircraft’s full development and design phase — next year.

In a joint statement released Wednesday, the partners said a joint venture agreement would be signed “soon” to create a new company in charge of delivering the project.

Japan’s Mitsubishi Heavy Industries, Italy’s Leonardo and Britain’s BAE Systems are set to be the project’s lead system integrators. However, building fighter jets involves a complex supply chain, meaning that GCAP will comprise more than one industry construct.

Several companies are set to come together as lead subsystem integrators in three broad domains. The first such industrial construct — in charge of sensors and communications — will bring together Leonardo U.K., Leonardo Italy and Mitsubishi Electric, while the second will see Rolls-Royce, Avio Aero and IHI work on engines and propulsion systems. Finally, MBDA U.K., MBDA Italy and Mitsubishi Electric will join forces to develop the aircraft’s future weapon systems. At the same time, these companies are expected to engage hundreds of subcontractors.

Along with the intergovernmental GIGO, which will be based in the British town of Reading, the proposed industrial construct will be headquartered in the United Kingdom “to achieve maximum alignment,” the partners said.

Both entities will work together with teams from across the three nations to support “capable, affordable and timely program delivery, including the 2035 in-service date,” they added.

The partners also confirmed that the GIGO’s first chief executive will be former Japanese Vice Minister of Defense for International Affairs Masami Oka, while an Italian will be the first to lead the future joint business construct.

The statement, along with the leaders’ pledges of support, should help allay concerns raised in the British media that the project could be significantly impacted by a U.K. strategic defense review expected next year.

While GCAP appears to be on schedule, the endeavor still faces a number of challenges, including financial constraints, workload distribution and an ambitious timeline. The project marks the first time that Japan is cooperating with countries other than the United States to meet a major defense requirement.

The future sixth-generation jet is intended to replace aging Air Self-Defense Force F-2 fighters, as well as British and Italian Eurofighters.

The twin-engine fighter, which is also intended for export, is set to function as a flying command center capable of controlling and coordinating other — likely autonomous — assets, with the aircraft viewed as “the centerpiece of a wider combat air system that will function across multiple domains.”

The leaders’ meeting in Brazil came as companies involved in the project have begun working on some of their own artificial intelligence-enabled drones that could potentially operate with the fighter, with both MHI and BAE Systems unveiling last month models of uncrewed systems that could potentially tie in with the program.