Soviet military spending and arms production fell last year, and the Kremlin leadership is developing a military strategy with more emphasis on defending the homeland and less on "external adventurism," the Pentagon said Tuesday.

The Defense Department's annual report on the Soviet military, entitled "Soviet Military Power 1990," described the Soviet Union as a nation so entangled in internal unrest that its military capabilities are hard to assess."Much that was once certain about the Soviet military is now open to debate," Defense Secretary Dick Cheney wrote in the publication's introductory essay. "It is not clear how that debate will be resolved."

Cheney said U.S. intelligence analysts believe Soviet military spending fell 4 percent to 5 percent last year compared with 1989, and that it cut back on some arms output.

The most pronounced cuts in arms production were in ground forces materiel, the report said. Tank production, for example, was cut in half, to about 1,700 tanks in 1989. Smaller but significant cuts occurred in artillery and multiple rocket launcher output.

The Soviets produced strategic, or long-range, offensive missile systems in 1989 at about the same pace as the year before, the report said. Production of bombers, fighters and fighter-bombers declined by an unspecified amount, while production of surface warships and submarines rose to 21 from 18 the year before.

Cheney, in his essay, cautioned that despite some signs of a less threatening Soviet military stance, the nation still has its nuclear missiles aimed at the United States.