MOSCOW, NOV. 1 -- The Kremlin stressed today a need to achieve as many strategic agreements with the Reagan administration as possible, despite the U.S. commitment to its Strategic Defense Initiative, a space-based antimissile sytem.

The official Communist Party newspaper Pravda said the decision on a third summit meeting between Kremlin leader Mikhail Gorbachev and President Reagan was "a very important step, which makes it possible to speak about the material base for a new political thinking."

Signaling a shift in policy, Gorbachev, senior Central Committee member Vadim Zagladin and Pravda praised the efforts for a U.S.-Soviet agreement to eliminate medium-range missiles -- to be signed at the upcoming summit -- and called for further strategic accords.

Until today, the Soviet press carried only cautiously worded dispatches about the plans for a summit. A week ago, for instance, Pravda punctuated an unsuccessful attempt by visiting Secretary of State George P. Shultz to set summit dates by saying that the summit would be possible only if the Reagan administration agreed to concessions on a planned space-age defense shield against nuclear weapons.

During a quickly planned visit by Soviet Foreign Minister Eduard Shevardnadze to Washington Friday, however, the two sides announced plans to hold a summit beginning Dec. 7 in the United States.

Here, the shift has already brought about a more upbeat assessment of U.S.-Soviet relations and possible further agreements.

In a book by Gorbachev released here today, he sounded a positive note about the overall prospects. Noting progress in reaching an accord on intermediate-range nuclear forces (INF), Gorbachev called for continuing the dialogue and pursuing additional U.S.-Soviet strategic agreements.

In the book, entitled "Perestroika: New Thinking for Our Country and the World," (perestroika means restructuring) prepared before the summit plans were completed, Gorbachev said that in previous talks he and Reagan had "sharp" exchanges and said "unpleasant things" to one another. "Of course, we could wait until the next administration," he said, "but we would rather come to agreement with the present one."

Zagladin, deputy head of the Central Committee's international department, announced in a televised interview today that the Soviet Union is ready to start "tomorrow" on negotiations with Washington to reduce short-range missiles as a follow-up to its plans to sign an INF accord.

In an interview from Moscow broadcast on Radio Luxembourg, Zagladin stressed a Soviet desire to dismantle short-range missiles, which are those with a range of less than 300 miles. "We are ready for liquidation of all missiles, and we are ready to do it tomorrow," he said, adding, "Now everything depends on the West."

Beyond the INF accord, however, the Soviet Union is concentrating its efforts on reaching agreement on sharp cuts in strategic nuclear arsenals, coupled with restrictions on Reagan's strategic initiative.

The Soviets are angling for agreements on both to be signed in the first half of next year during a tentatively scheduled follow-up meeting in Moscow, according to Soviet officials.

In a news analysis in Pravda today, Foreign Editor Evgeniy Grigoriev stressed the agreement that Reagan and Gorbachev will discuss an accord to reduce strategic weapons by 50 percent and prevent development of space arms when they meet next month.

"To untie that knot is difficult but possible," Grigoriev said, in a reference to the difficulties in reaching a compromise on strategic cuts and restrictions on space defense.

One reason the Kremlin is making fresh appeals for arms control agreements is to offset burgeoning domestic political tensions, western diplomats in Moscow said.

According to official accounts of a Central Committee session Oct. 21, leading Soviet officials criticized Boris Yeltsin, the Moscow party leader who has been an outspoken proponent of Gorbachev's changes.