The Japanese computer industry is being challenged to rethink its strategy. Its alleged involvement in ''stealing'' secret data from the International Business Machines Corporation puts double emphasis on a strategy shift.
Since the 1960s, the Japanese have been producing computers compatible with IBM computers, but at a lower cost. Its first strategy was to buy an IBM machine on the open market, strip it, and copy it.
''It took us six years to copy the IBM 360 model they marketed in 1964,'' an engineer recalls.
More recently, the Japanese have found an easier method: collecting data from every available source on each new IBM model and its accompanying software.
But industry analysts say IBM has been fighting back. Its latest models, for example, contain a number of features that are making it increasingly difficult for Japanese makers to produce compatible models.
They say this could explain the element of desperation that led Hitachi Ltd. and Mitsubishi Electric Corporation to fall into an elaborate FBI trap, which was laid to catch IBM's information thieves.
A leading analyst said: ''The increasing difficulty in unlocking the secrets of the new IBM machines is forcing Japanese companies to review not only their entire IBM-copying practice, but also their global strategy designed to reshape the computer industry under their leadership.''
At present, IBM dominates the world market for computers. Japanese computermakers, eager to chip away at IBM's market hold, are trying to develop a ''united anti-IBM front.''
The top Japanese maker, Fujitsu Ltd., for example, has partnerships with West Germany's Siemens AG and Britain's ICL in the field of large computers.
Of the two companies in the industrial espionage case, Mitsubishi on June 7 signed a ''cooperation agreement'' with Sperry Corporation, a US computer and electronics company. The agreement calls for joint development of information-processing products and services. The other company in the case, Hitachi, has been negotiating a possible partnership with Burroughs Corporation.
Even before the blaze of publicity over the IBM case, government officials say, it was obvious that high technology, especially computers, was the new economic battleground between the two countries.
Sources at Japan's Ministry of International Trade and Industry say the Reagan administration has switched from demands for conventional market-opening measures to complaints that Japan is ''not playing fair'' in the vital high-technology ''frontier industries.''