JAPAN'S prospective role in the Strategic Defense Initiative (SDI or ``star wars'') looms large. The United States is eager for the contribution Japanese technology could make in this still nebulous program; Japan's Defense Agency, meanwhile, is seriously evaluating the country's options within SDI. It is doubtful, however, whether SDI is the best vehicle for Japan's playing an expanding international role.
To date most of the uncertainty among the Japanese over their role in SDI has centered on rather mundane issues: whether Japan is being suckered into a strategic trap by the US and whether Foreign Minister Shintaro Abe's pointed caution in the face of Prime Minister Yasuhiro Nakasone's carefully modulated enthusiasm will advance Mr. Abe's campaign to become prime minister. There are far more important reasons to be concerned about Japan's getting nudged into star wars. It is becoming proverbial in Japan that SDI is a double-edged sword.
According to this view, the risk that US-Japanese cooperation on SDI may stir up the now torpid Japanese peace movement would be more than outweighed by the benefits of bolstering Japan's defense consciousness as a partner of the US in an antinuclear strategic program.
This view appears persuasive at first glance because it uses Japan's renowned nuclear ``allergy'' so as to overcome the drawbacks of that inhibition and induce greater defense cooperation. The ``double-edged'' metaphor is misleading, however: This sword has many edges.
The most important other ``edges'' involve the danger that Tokyo could see its entry into SDI research as a way to preempt US retrenchment toward an SDI-based self-reliance; as a way for Japan to placate US critics of the stinginess of Japan's defense budget; or both.
Making use of Japanese fear (however unwarranted) that the US will gradually abandon its allies as it moves toward an SDI-protected nuclear ``fortress America'' could be a productive way to motivate the laggard Japanese.
Far more troubling is the very real prospect that the Japanese might latch on to SDI as a way to deflect existing US pressures on Tokyo to do more in its own defense. By its very open-endedness, SDI research can be considered a budgetary bottomless pit. This is, in part, why so many US critics of SDI are exercised about it. That concern fits Japan's predisposition to see wasted defense money as a drain on economic performance damaging to the superpowers.
This is what Japan's minimalist defense policy is designed to avert, while the US subsidizes its security. Should US frustration with subsidizing Japanese defenses -- especially when Japan is enjoying a $50 billion annual trade surplus with the US -- lead Washington to escalate its pressures, it is easy to visualize a subtle shift in Tokyo's response.
Rather than throw money down what they consider a defense rathole, the Japanese could tilt toward spending increased defense funds on almost perpetual SDI-oriented research, with many dual-use technological spinoffs that could benefit the Japanese economy.
This approach would allow Tokyo to mollify the US by spending an appropriately larger percentage of its GNP on such vague future-oriented security measures while avoiding doing anything concrete in conventional, real-world defenses. Instead of standing beside the US in the trenches of superpower tensions, shouldering common burdens, Japan might opt to perform its duty in a low-profile, safe, rear-area research laboratory.
If the US isn't careful on SDI negotiations with Japan, it could end up providing Tokyo with an easy way out of its security dilemma with the US, which threatens to spread to broader trade problems. Such a development would give Japan new leverage in deflecting additional US pressures in security and trade.
This is not to suggest that Japan be deflected from its SDI options. Japan's potentials for contributing to such an arcane endeavor are great and should be used but not to the extent that it stimulates unwarranted fears in Japan about US motivations or unwarranted gullibility in the US toward Japanese response. In short, the US should pursue SDI with Japan, but in a balanced fashion that makes Japan a responsible partner in all respects of shared security.
Edward A. Olsen is associate professor of national-security affairs and coordinator of Asian studies at the Naval Postgraduate School, Monterey, Calif.