TOKYO -- Lockheed Martin has proposed that Japanese companies be responsible for more than half of the development and production of a next-generation fighter jet that Japan wants to introduce in 2030, Nikkei learned Wednesday.

Lockheed is offering Japan an upgraded version of the existing F-22. The U.S. currently bans exports of the plane known as "the Raptor," which is considered the world's most powerful fighter, has stealth capabilities and is armed with eight air-to-air missiles.

The U.S. aircraft manufacturer's decision to open the production to Japan comes out of the belief that there is little risk of technology leaks. The company also says providing the jet to Japan would contribute to the security of Asia. If the share of work pans out as proposed, it would strengthen Japan's defense industry and the Japan-U.S. alliance.

Lockheed's proposal comes in response to concerns in Japan that American companies might monopolize the development and production of the upgraded warplane, leaving little room for Japanese partners' involvement. The company calls the plan a Japan-led framework.

The next-generation fighter will replace Japan's F-2 jets, scheduled to retire around 2030. Tokyo initially looked for ways for Japan Inc. to completely develop a successor on its own, hoping to boost the domestic defense industry's orders, but the idea proved unfeasible due to technological and cost hurdles.

The Japanese government sees Lockheed's proposal, which could deliver high performance at reduced development costs, as the most promising alternative.

The next-generation fighter program is estimated to cost about 6 trillion yen ($54.2 billion), including development, acquisition and maintenance. Some voices are citing a need to update the F-22, which has been deployed since around 2000, and Lockheed's plan has the benefit of lowering upgrade costs shouldered by the U.S.

Although Japan produced 60% of the jointly developed F-2, the U.S. handled engine development since Japan did not have the basic technology at the time. But Lockheed has expressed a willingness this time to shift development and production of new engines to major Japanese heavy machinery maker IHI in the future. If IHI's XF9-1 jet engine is adopted, Japanese companies could be responsible for more than 60% of the total work.

In addition, the exports of high--margin military equipment for the project could ease the U.S. trade deficit with Japan.

Mitsubishi Electric's fighter jet electronics system could be adopted, and Mitsubishi Heavy Industries will handle the development and production of wings, according to the plan. The aircraft's body, engines and the fighter system are to be made in the U.S., but Lockheed intends to use more Japanese-made components, incorporating them gradually until Japanese companies play a central role in development.

To hasten development, Lockheed will send Japan F-22s that have not been deployed by the U.S. Air Force so that it can grasp its performance in advance.

The updates will improve the plane's main wings and allow more fuel to be loaded, increasing the jet's range to about 2,200 km so it can be used to defend isolated islands and other missions.

Although the F-22 has the most advanced stealth abilities in the world, it requires a special coating that is laborious to maintain. Maintenance will be simplified by using the same material as the F-35 stealth fighter, making it easier to perform drills and deploy for battle.

One challenge is the cost. Lockheed estimates the price of the next-generation fighter will be far higher than the F-35's 15 billion yen-per-jet price tag. Lockheed estimates the price of a next-generation F-22 at about 24 billion yen if it is part of an order of 70 aircraft. Producing 140 of the jets could reduce the unit price to about 21 billion yen.

There is also concern that including Japanese companies, which have not independently developed a fighter jet in recent years, could complicate production and ramp up costs. Lockheed initially estimated that the F-35A would cost about 10 billion yen per jet. Costs temporarily rose to 17 billion yen, however, when assembly was given to Japanese companies, a cause for concern this time.

Some doubt that the U.S. will fully disclose core technology for the world's most powerful fighter jet. Although Lockheed plans to outfit the jet with several Japan-made weapons in an effort to include as much domestic technology as possible, the U.S. will initially be responsible for most of the work, with Japanese companies gradually joining the process later. It is unclear, however, when development will proceed to that second stage.

"It is likely that the U.S. will not want to give up such core technologies as fighter systems and software," said Heigo Sato, a professor at Takushoku University. "The technological spillover to Japanese companies would be limited if they mostly receive subcontracting work."

Although Mitsubishi Heavy assembles the F-35, which has begun deployment, it has been pointed out that having that job has hardly improved the company's technology knowledge. The U.S. Congress also turned down Japan's request for the F-22 to succeed the F-4 a decade ago because of hesitance about transferring military technology.

Should technology transfers from the U.S. slow, it may hinder Japan's continued development of fighter jet technology.

Japan must choose whether to develop its own jet, jointly develop with another country or update existing aircraft. Tokyo will make its decisions at the end of the year in its revised medium-term defense program. Boeing and Britain's BAE Systems have also made submitted proposals to upgrade existing planes.