A House Armed Services Committee panel, after months of analysis, has divided sharply along partisan lines in its conclusions on the Soviet military threat, a split that foreshadows major disagreements on fundamental questions of U.S. defense spending in upcoming budget hearings.

The Democratic members of the Defense Policy Panel, led by Chairman Les Aspin (D-Wis.), endorsed findings that the Soviet conventional threat "is becoming an empty threat" which will allow the United States to reduce its military "selectively without jeopardizing our security."

But, in a pointed rebuke, all 15 Republican members of the panel rejected the report entitled, "The Fading Threat: Soviet Conventional Military Power in Decline."

"Endorsing this report is tantamount to believing that the Soviet Union is already militarily impotent and not a global power to be reckoned with," said ranking Republican Rep. William L. Dickinson of Alabama in a blistering rebuttal released simultaneously with the report yesterday.

"While we believe that there has been a decrease in the Warsaw Pact conventional threat to NATO, we reject the unwarranted certainty with which the report dismisses current and projected Soviet conventional and nuclear military capabilities," Dickinson continued.

The Defense Policy Panel conducted open and closed hearings with senior intelligence officials, top Soviet military leaders and leading U.S. authorities on the Soviet military in preparing its 310-page report.

Committee representatives from both parties toured military facilities throughout the Soviet Union last year as part of its assessment.

Key findings, which the Democratic majority said should be used "as a basis for deciding our defense priorities," include:

The Soviet conventional threat to Europe has diminished greatly and because of domestic turmoil, political change and economic troubles, cannot be revived. The Soviet conventional threat in other parts of the world has declined also, although "not as precipitously as in Europe."

Even if embattled Soviet President Mikhail Gorbachev fell from power, "large-scale Soviet military interventions outside of Soviet territory seem beyond the Red Army's powers."

While the Soviets continue to modernize strategic forces, the risk of nuclear war "probably has declined," reflecting "changes in Soviet intentions under the Gorbachev regime" and reduced possibilities that a conventional conflict in Europe would escalate into a strategic war.

The Democrats accused the Bush administration, particularly Defense Department officials, of being "overly cautious, even grudging, in its appreciation of how the Soviet threat is changing."

The report added that "the debate . . . is not over intentions as Defense Secretary {Richard B.} Cheney believes, but over the reversibility of the reduced threat to the U.S. and NATO."

Republican panel members, in a three-page dissent included in the report, said, "We believe the overconfident tone of this report is unjustified" and helps "to create the illusion that the U.S. can rapidly diminish its own capabilities."

"There is too much uncertainty and instability out there to let fiscal concerns exclusively drive our national security policy," Dickinson said in a statement accompanying the report.

Both party members agreed on one statement in the report: "The worst thing the U.S. could do is to cut defense spending too much."

The Democratic conclusion, added, however, "The next worst thing we can do is spend too much."

While the budget deficit will be the biggest influence on the final size of the defense budget, the debate over the Soviet military threat will be crucial to deciding which individual weapon systems and programs will be cut.

The Pentagon announced yesterday that Cheney will return to Washington from Turkey Tuesday evening to take part in the budget deliberations, skipping scheduled stops to see defense officials in Spain and Portugal.

The administration, in its proposed $306 billion defense budget for 1991, has recommended cuts in conventional weapons programs, while continuing healthy increases in strategic programs.