The pace of Japan's defense buildup is likely to be one of the first casualties of Prime Minister Yasuhiro Nakasone's stunning setback in the Dec. 18 election.
Mr. Nakasone is struggling to form a viable coalition among the factions composing the ruling Liberal Democratic Party, so as to be reelected premier when the new Diet (parliament) is convened at the end of this month.
Meanwhile, the Defense Agency is already engaged in a controversy with the powerful Finance Ministry over the defense budget for 1984.
Kazuo Tanikawa, director-general of the Defense Agency, was one of three members of the Nakasone Cabinet who lost his Diet seat in the election debacle. Mr. Tanikawa was a conscientious minister who made a good impression both on American and on Japanese defense officials. But he comes from a constituency near atom-bombed Hiroshima, and his vote totals suffered from the hawkish stance of the Nakasone Cabinet.
The Reagan White House has been pressing Japan to increase defense spending in order to help counter the massive growth in Soviet military strength in the Far East, especially in the seas and air surrounding Japan. But the Japanese defense budget remains at less than 1 percent of gross national product (GNP).
Defense sources say the Finance Ministry is even trying to get the defense budget for 1984 reduced, within the framework of the 1 percent of GNP ceiling. In August the ceiling for the increase in defense spending for 1984 was set at 6 .88 percent of the current budget. This would mean an increase of some 189 billion yen ($804.3 million) and a total defense budget of 2 trillion 943 billion yen.
Since then, however, personnel costs have risen and the Defense Agency is requesting a further 0.9 percent increase in the budget to absorb these costs. The Finance Ministry, however, says the personnel costs should be squeezed out without further increasing the total defense budget.
At stake is the Defense Agency's plan to buy 21 F-15 Eagle fighter aircraft, 11 P3C Orion antisubma-rine patrol aircraft, three frigates, and one submarine during the coming fiscal year beginning in April 1984.
A powerful prime minister can settle ministerial disputes of this kind. But Nakasone's defeat damaged his ability to show forthright leadership in areas such as these, where Japan's commitments as a United States ally must be balanced against heightened domestic opposition to the idea of bigger defense budgets.