In theory, Japan is ready to export military technology, and even weapons, to the United States. But translating theory into practice may be a long and difficult task.
The US first floated the idea of importing Japanese military technology at a conference with Japanese military officials in Washington last July.
Joji Omura, director of the Self-Defense Agency, was one who immediately saw merit in the suggestion, especially as a means of meeting American pressure on Japan for a bigger military budget and larger regional military role.
Informed sources say that so far Prime Minister Zenko Suzuki and other senior cabinet members are cool to the whole idea.
Suzuki rejects the idea Japan is getting a ''free ride'' on defense. In recent days he has expressed his irritation at American pressure for more Japanese defense spending.
Some observers suggest the prime minister will not want to risk a parliamentary and public uproar that could breath new life into Japan's languishing anti-war movement.
What exactly the US wants remains unclear. But possible cooperation in the fields of super large-scale integrated circuits for computers, robots, ultraviolet devices for night vision, and laser technology were all mentioned when Yutaka Wada, director of the Defence Agency's equipment bureau visited Washington in September.
The consensus of Japanese government agencies is that it is legal for Japan to export military technology to the US.
But there are extremely sensitive political considerations that demand caution.
These revolve around the present ''peace constitution,'' in which Japan has basically forsworn the potential to wage an aggressive war (as distinct from a defensive one).
Out of this grew three principles adopted by the ruling Liberal Democratic government in 1967. They forbid export of weapons to (1) communist countries, (2 ) countries against which a United Nations arms embargo is being applied, and (3 ) any country that could potentially become involved in a military conflict.
As the latter provision could apply to every nation on earth, that effectively meant no weapons exports in any shape or form.
The government has been forced to deliberate in the past few months over whether the United States is exempt from the three principles.
It was found that the Japan-US Mutual Defense Agreement (MDA) contained a provision for technical cooperation, thus allowing Japan to export its advanced military-related technology.
But a senior Foreign Ministry official went one step further this week when he told a Diet committee that Japan could also supply the US with weapons.
Shinichiro Asao, director of the North American affairs bureau, said this could be possible under Article 3 of the Japan-US Security Treaty, which covers ''mutual cooperation and aid.''
Another aspect has been opened up by the Defense Agency, which now says that in the event of an emergency in East Asia, Japan can go far beyond assisting the US simply by providing bases on Japanese soil.
Akira Shioda, a Defense Agency official, told a Diet committee the government could help American forces with logistical support, such as procurement and transportation of supplies.
As far as export of weapons technology is concerned, the Foreign Ministry appears to be most enthusiastic, with officials privately saying negotiations with Washington could begin within this year.
Experts maintain the three principles have no force of law and are merely an expression of government policy. They say the Japan-US Security Treaty takes precedence and that the principles will still apply to all other countries.
The Defense Agency contends that bolstering the US defense capacity will contribute to the peace and security of Japan and of east Asia in general.