Rishi Sunak is set to announce a collaboration between the UK, Italy and Japan to develop a new fighter jet that uses artificial intelligence.
The prime minister says the joint venture aims to create thousands of UK jobs and strengthen security ties.
The nations will develop a next-generation fighter that will eventually replace the Typhoon aircraft due to enter service in the mid-2030s.
The new Tempest jet is expected to carry the latest weapons.
It is already underway to develop a fighter jet that provides speed stealth and uses advanced sensors and even artificial intelligence to assist the pilot when overwhelmed or under extreme stress.
It could also fly without the involvement of a pilot if necessary and could fire hypersonic missiles.
But building such a complex aircraft is extremely expensive: developing the F35 jet was the most costly program ever undertaken by the Pentagon, so Britain has been looking for partners.
Italy was already on board, and the addition of Japan was a significant move when Britain built closer ties with allies in the Indo-Pacific region concerned about a more assertive China.
Other countries could still join the program. France, Germany and Spain are already working together on their separate design, as is the United States.
For the UK, this deal is about security and economics. The hope is that developing a new fighter jet can create and sustain thousands of UK jobs and open the door for more arms exports.
Sunak will launch the first major phase of the program during a visit to RAF Coningsby in Lincolnshire on Friday.
Ahead of the visit, he said: “The security of the UK, both today and for future generations, will always be paramount to this government.
“That is why we must remain at the forefront of advances in defence technology, outmanoeuvring and outmanoeuvring those who seek to harm us.
“The international partnership that we have announced today with Italy and Japan aims to do just that, underlining that the security of the Euro-Atlantic and Indo-Pacific regions is indivisible.
“The next generation of combat aircraft we are designing will protect us and our allies worldwide by harnessing the strength of our world-leading defence industry, creating jobs and saving lives.”
John Healey, the Labor Party’s shadow defence secretary, said his party supported the association but warned against training.
“Ministers need to make it clear how this fits in with broader plans for the future of the RAF, including how they will avoid delays in the training of fast aircraft pilots,” he said.