TOKYO >> The defense ministers of Japan, Britain and Italy on Thursday signed an agreement to establish a joint organization to develop a new advanced jet fighter, as the countries push to bolster their cooperation in the face of growing threats from China, Russia and North Korea.

The three countries had agreed last year to merge earlier individual plans — for Japan’s Mitsubishi F-X to succeed the retiring F-2s developed with the United States and Britain’s Tempest — to produce the new combat aircraft for deployment in 2035.

Japan, which is rapidly building up its military, hopes to have greater capability to counter China’s rising assertiveness and allow Britain a bigger presence in the Indo-Pacific region.

Defense Minister Minoru Kihara at a joint news conference with his British and Italian counterparts, Grant Shapps and Guido Crosett, said that co-developing a high performance fighter aircraft is “indispensable to securing air superiority and enabling effective deterrence” at a time Japan faces an increasingly severe security environment.

Kihara said no individual nation can defend itself today, adding that securing the technology and funding to develop an advanced fighter jet involves large risks. The joint trilateral Global Combat Air Program is a “historic program,” he said, that enables the three countries to work together to create a new fighter jet while reducing risks.

Under the plan, a joint body called the International Government Organization will manage the private sector joint venture — which includes Japan’s Mitsubishi Heavy, Britain’s BAE Systems PLC and Italy’s Leonardo — to oversee the aircraft’s development. The organization is tasked with distributing work in different areas, such as the engine and avionics.

The organization, known as GIGO, will be headquartered in Britain and headed by a Japanese official, and the joint venture will be led by an Italian representative, Kihara said. The top posts will rotate every few years, Japanese defense officials said.

Japan is moving ahead despite delayed approval at home to ease its current policy that bans the export of lethal weapons. The restriction under Japan’s postwar pacifist Constitution does not allow the country to sell a jointly developed fighter jet and possibly complicates the project, since Britain and Italy hope to be able to sell the new combat aircraft.

A Japanese government panel has been discussing the easing of military sales and agreed to relax restrictions on the transfer of licensed technology and equipment. But it recently postponed a decision on easing the policy for the joint fighter jet until early next year.

Defense officials refused to discuss how the situation would possibly affect the joint project.

The project is the first time Japan will participate in a multinational organization to jointly develop new military equipment.

To counter growing threats from China, North Korea and Russia, Japan has been expanding its defense partnerships with countries in Europe, Southeast Asia and the Indo-Pacific, including Australia and the Philippines.