TOKYO, SEPT. 18 -- Japan's Defense Agency has formally acknowledged a fundamental military fact of life in the post-Cold War world: The Soviet menace is fading.

Japan's top military brass released the 1990 edition of its white paper on national defense today, and, for the first time in more than a decade, the term "latent Soviet threat" appears nowhere in it. The 350-page document refers to Soviet troops and Soviet forces, but never uses the word kyoi, or "threat," to describe the Russian military.

The absence of the two script characters that form the word "kyoi" made front-page headlines and got top billing on television news programs. This is partly because the Japanese have an intense fascination with their language, but mainly it reflects the general shift toward the better in Soviet-Japanese relations, a change that is palpable here.

Soviet Foreign Minister Eduard Shevardnazde's visit to Japan two weeks ago was a clear success, and both nations are now working on ways to improve their historically strained relations. The planned visit here next April by Soviet President Mikhail Gorbachev -- known jauntily in Japan as "President Go" -- should further the friendship drive.

The Defense Agency document details significant manpower reductions in Soviet land, sea and air forces in East Asia and says that the risk of aggression has been reduced. But it adds that the number of Soviet troops is still "enormous."

Asked why the Russian military presence near Japan is no longer described as a threat, the defense official who supervised the report said that the change was more predictive than descriptive. "Out of the hope," he said, "that they would further decrease their forces {in Asia}, we decided not to use the word 'threat.' "

The document says that the Soviets have been reducing the number of troops and weapons in Asia but notes that they also have been replacing outmoded military gear with new models, which in most cases are more powerful than the old ones.

In a position that will be familiar to observers of the American military, the white paper contends also that the absence of a Soviet threat does not mean the defense budget can be cut.

In fact, the Defense Agency asked recently for a 5.8 percent budget increase to buy new high-tech weapons, especially for the Japanese navy. It will also go to enhance living conditions for military personnel, because the Self-Defense Force -- like every other employer in the booming Japanese economy -- is having trouble recruiting good people in a highly competitive labor market.