MOSCOW, SEPT. 20 -- The Soviet armed forces newspaper today called an American-Soviet decision to eliminate medium- and short-range nuclear missiles a "breakthrough" that could pave the way to cutbacks in strategic nuclear weapons.

The daily Krasnaya Zvezda (Red Star) said that after the talks in Washington between Soviet Foreign Minister Eduard Shevardnadze and U.S. Secretary of State George P. Shultz, the world had reached a crossroads that opened new vistas for further nuclear disarmament.

An agreement on the medium-range weapons "in its turn should create a powerful momentum toward resolving the key issue -- the reduction of strategic offensive weapons," said the newspaper's political observer, Manki Ponomarev, in a column that was entitled "At the Turning Point."

"If one were to compare the development of international relations to climbing a steep, high mountain, then I think one could say we had reached a pass from which the road to a nonnuclear and safe future is visible," he said.

The article made no mention of the U.S. Strategic Defense Initiative, which Moscow for several years has described as the greatest obstacle to reductions in nuclear arsenals.

This shift in the Soviet Union's rhetorical stand suggests a determination to keep the path to a late fall summit meeting between President Reagan and Soviet leader Mikhail Gorbachev clear of obstacles and to speed up the negotiating schedule during the remaining 15 months of the Reagan administration.

In its weekly international affairs column today, the official Soviet Communist Party newspaper Pravda hailed the "good news" from Washington last week. "For the first time in the whole history of the existence of nuclear weapons . . . an agreement has been successfully reached to eliminate two classes of nuclear missiles," the Pravda column said.

"We hope that the meeting {between Gorbachev and Reagan} will be a point of departure for new major steps toward the full liquidation of the threat hanging over mankind."

In an article that was published in Pravda last week, Gorbachev laid out the Soviets' preferred timetable, calling for an agreement on medium-range weapons by the end of this year and a reduction in strategic weapons by the first half of next year.

Analysts on both sides have stressed that deep cuts in the superpowers' strategic arsenals carry more military significance than the elimination of medium- and short-range missiles.