The United States and the Soviet Union return to the arms negotiations in Geneva today far apart on the central issues, especially the question of limits on President Reagan's "Star Wars" missile defense plan.

Statements from Washington and Moscow in the past several days suggest some movement on peripheral questions is likely in the course of the second round of the negotiations, which is scheduled to last until July 16.

But on the big issue of space weapons, which the Soviets have made their top priority, there is no hint of an early compromise. On the contrary, the increasingly open statements of the Soviet position, including remarks by Soviet leader Mikhail Gorbachev in Moscow yesterday, suggest that the deadlock on this issue is deep and definite.

In remarks at a Kremlin dinner in honor of visiting Italian Prime Minister Bettino Craxi, Gorbachev warned that U.S. insistence on going ahead with a space-based missile defense system may bring about "not only the subversion of the Geneva talks but the scrapping of every prospect for an end to the arms race."

At the same time, he hinted at a small but potentially significant shift in the position reportedly taken by Soviet negotiators in the first six-week session of the negotiations, which ended April 23.

Washington Post foreign correspondent Celestine Bohlen reported that Gorbachev last night renewed proposals made in 1983 by a predecessor, Yuri Andropov, to freeze Soviet medium-range missile deployments in Asia in the context of an overall agreement. U.S. arms control adviser Paul H. Nitze said May 1 that in the first Geneva round, Soviet negotiators backtracked from this position, insisting on "no restraints" on their medium-range deployments in Asia.

The Gorbachev speech is the latest in a series of public statements of the Soviet negotiating positions as the resumption of the Geneva talks neared.

Gorbachev made no mention in his speech of the 1983 Soviet offer to reduce strategic offensive delivery systems by one-fourth as part of an overall arms agreement. The new Soviet leader referred to such a cut in a Warsaw speech April 26 as "an opening move" suggested by his side, but the State Department said no such proposal had been made by the Soviets in the opening Geneva round.

Reagan administration officials said they anticipate that at some point the Soviets will unveil a version of this cutback plan in the talks as evidence of what can be accomplished if the United States agrees to limit Star Wars.

Ambassador Max M. Kampelman, accompanied by other members of the U.S. negotiating team, said on arrival in Geneva yesterday that "we continue to have the flexibility that we need to move forward."

U.S. officials said that the basic U.S. posture remains unchanged from the first Geneva round but that President Reagan has approved "elaborations" and "refinements" of the positions to be put forward at the bargaining table.

Ambassador Viktor P. Karpov, the chief Soviet negotiator, said in his arrival statement that "renunciation of the development, including research, testing and deployment, of space arms would open the way to radical reductions in nuclear arms."

U.S. sources said Soviet positions laid down in the first round in Geneva included:

* A comprehensive ban on "scientific research," development, testing and deployment of "space strike arms," which Moscow defines as arms designed to strike targets in space from Earth or to strike targets on Earth from space. All the other Soviet offers were conditional on U.S. acceptance of this ban.

Although Soviet officials have conceded at times that some types of research studies cannot be verified by spy satellite or other available means, Foreign Minister Andrei Gromyko reportedly defended the proposed ban on "scientific research" during his meeting with Secretary of State George P. Shultz in Vienna on May 14.

* A U.S.-Soviet moratorium on development and deployment of strategic offensive arms and intermediate-range arms for the duration of the arms negotiations, to be followed by reductions.

* A halt to development and deployment of new types of strategic weapons such as the U.S. MX missile and B1 bomber and certain Soviet weapons.

Though the Soviets have spoken of "radical reductions" in strategic arms if the United States bans Star Wars, no specific cutbacks were proposed by Soviet negotiators in the first round at Geneva, U.S. officials said.

* A ban on further development, testing and deployment of all cruise missiles with a range exceeding 600 kilometers, whether ground-launched, sea-launched or air-launched, and wherever deployed.

* A halt to U.S. medium-range missile deployments in Western Europe in return for a halt to Soviet deployment of additional SS20 missiles in the western part of the Soviet Union and medium-range missiles in Czechoslovakia and East Germany.

The U.S. positions put forth in the first Geneva round were much more general. But the U.S. negotiators had the authority then -- and retain it in the new round -- to go into specifics about cutback proposals if the Soviets are willing to bargain in detail. This did not happen in the first round, U.S. officials said.