IN significantly boosting Japan's defense budget, the government of Prime Minister Yasuhiro Nakasone is taking a bold step that promises to please the Reagan administration but could work against his own political support within the Japanese electorate. The defense numbers by themselves might seem somewhat inconsequential to a North American or European accustomed to huge defense outlays. The Japanese government's new defense plan for the period 1986-90 calls for cumulative military expenditures of $76.5 billion.
But what is significant about the Japanese five-year defense plan is the percentage increase: Under current economic projections Japan's total defense spending during the five-year period for the first time would likely exceed 1 percent of the nation's gross national product. Indeed, the defense spending would constitute roughly 1.04 percent of Japan's GNP, slightly breaking the present 1 percent margin.
Maintaining a 1 percent cap on defense spending, as a percentage of GNP, has been an almost sacrosanct limitation in Japan, which has a large and vocal antimilitary constituency. Moreover, among the population at large there is considerable unease about any possible return of the strong military establishment that dominated Japanese society through the first three decades of this century -- until it was discredited by Japan's defeat in World War II.
The world community cannot help sharing Japanese unease about the increase in defense. As these columns have long noted, it is far preferable to spend money for peaceful pursuits than for weapons of warfare. Under most circumstances, there can be little occasion for joy when military budgets are increased.
At the same time, most Western nations, and certainly Washington, should support what the Nakasone government has done. Japan, after all, is now the second-largest industrial power within the noncommunist community of nations. It enjoys a trade surplus with almost every major commercial partner with which it does business. And given the substantial levels of direct investments abroad by Japanese companies, particularly in the United States, Japan is becoming a major creditor nation on the world scene.
In short, Japan should rightly be doing far more than it has been doing in filling a ``superpower'' role within the global community equal to its economic and industrial prowess. For all practical purposes, the US provides the essential military and strategic defense umbrella protecting Japan -- and Japanese industry.
One of the main reasons Japan has ample financial resources to support its vigorous industrial and trading policies abroad is that the US uses so much of its own financial resources for defense. In the US, defense outlays for fiscal year 1986 add up to an estimated 7 percent of GNP -- far above the 1 percent range of GNP pegged for defense by Japan.
Pressures will now be considerable within Japan to get defense outlays back down to or below the 1 percent level. Yet, on balance, increasing defense seems appropriate, given Japan's global standing.