The Soviet Union's ruling Politburo officially adopted its position for the U.S.-Soviet arms talks today without elaborating on what it will be.

The Politburo's review of "questions related" to next week's meeting in Geneva was the top item listed in the weekly Politburo minutes issued by the official news agency Tass.

"An appropriate decision on the Soviet Union's position was taken," Tass reported. The same item led the television evening news program.

The prominent mention of such a Politburo discussion was considered unusual by western diplomats here who took it as a signal that what Soviet Foreign Minister Andrei Gromyko says in Geneva next week to U.S. Secretary of State George P. Shultz has the full backing of the Kremlin. It also reflects the importance Moscow has attached to the talks, diplomats said.

Commentators in the official press emphasized again today the high priority given by the Soviets to a halt in the development of space weaponry. The talks will also deal with strategic and medium-range offensive weapons, but curtailing the American "Star Wars" program, most immediately the testing of antisatellite weapons, long has been at the top of the Soviet agenda.

Writing in the government newspaper Izvestia, news analyst Valentin Falin dismissed the Reagan administration's argument that an "umbrella" of defensive weapons in space could reduce the nuclear threat.

"The essence of the U.S. calculations is revealed by other words, other admissions: He who controls space controls the earth," Falin wrote.

Falin argued that a U.S. insistence on its Star Wars program could stall any talks, just as he said NATO's deployment schedule for missiles in Europe held up medium-range missile talks in 1983.

"Hence, if the United States' decision to put arms into space is the final one, a high pace of talks -- if they are to start at all -- cannot be expected from the Americans, for the United States space program is planned for two or 2 1/2 decades," he said.

"The U.S.S.R. is for placing reliable barriers to the use of nuclear weapons and is convinced that there is no need for space umbrellas for this," Falin wrote.

Tass commentator Yuri Kornilov echoed the same theme tonight, warning that a race in space weapons would "give an impetus to the arms race in other areas."

"The U.S.S.R. suggests that a whole range of attack space weapons, including antisatellite and antimissile, space-based systems as well as any ground-, air- or sea-launched systems intended to hit targets in space, be banned and eliminated," Tass said.