MOSCOW, JULY 23 -- The Soviet Union today listed four major obstacles still blocking a U.S.-Soviet agreement to eliminate medium- and short-range nuclear missile arsenals and identified the key hurdle as the American-controlled nuclear warheads for West Germany's 72 Pershing IA short-range missiles.

Elaborating on the new arms offer Kremlin leader Mikhail Gorbachev made yesterday, senior Soviet officials, in a press conference today, called on Washington to help remove the obstacles and clear the way for a U.S.-Soviet summit.

Western diplomats here predicted that a U.S.-Soviet dispute over the Pershing issue would drag on through the summer and dominate the arms talks in Geneva.

Gorbachev offered the "global double zero" agreement in an interview released here yesterday, dropping a condition that 100 Soviet medium-range SS20 warheads in Asia be excluded from the proposed treaty eliminating all medium-range missiles in Europe. In exchange, he proposed that the United States agree not to deploy the 100 medium-range warheads it would be allowed to base in Alaska or elsewhere in U.S. territory.

Gorbachev thus accepted the U.S. position calling for a total elimination of medium-range missiles -- those with ranges of between 600 and 3,500 miles. The United States has already accepted Gorbachev's proposal to eliminate shorter-range (300-to-600-mile) missiles.

Soviet Deputy Foreign Minister Yuli Vorontsov told journalists today that if such a "double zero" treaty is completed by U.S. and Soviet negotiators in Geneva, "a possibility will open up for it to be signed at the summit level." But both Vorontsov and Army Chief of Staff Sergei Akhromeyev stressed that the 72 Pershing warheads remain a key impediment to concluding the treaty.

{In Washington, White House National Security Adviser Frank C. Carlucci said the United States does not accept the Soviet demand that the 72 Pershing warheads be withdrawn. Senior U.S. officials said that compromises could be reached, however, on the three other issues raised by the Soviets. Story on Page A18.}

The proposed treaty, as revised by Gorbachev's comments this week, would involve the elimination of all Soviet SS20 and SS4 medium-range missiles, and short-range Soviet systems in both the European and Asian parts of the Soviet Union. All American medium-range Pershing II and cruise missiles deployed in Western Europe also would be eliminated, as well as all short-range U.S. systems in Europe and Asia.

The 72 single-warhead Pershing IAs, which have a range of up to 460 miles, were turned over to West Germany by the United States in the 1970s. The United States and West Germany both argue that the missiles are outside the scope of a U.S.-Soviet treaty, even though their nuclear warheads remain under U.S. control.

"What kind of 'global double zero' option would there be if the U.S. left 72 of its warheads behind?" Vorontsov asked. Agreeing that the Pershing IA missiles are the property of West Germany, Akhromeyev said, "The point at issue is the scrapping of all the U.S. warheads to these missiles."

In addition to the Pershings, Akhromeyev listed three other obstacles to a "global double zero" treaty:

1. Genuine destruction of all medium-range missiles, with no opportunity for either side to convert them into other weapons. The United States has proposed removing one stage from its medium-range Pershing II missiles, turning them into shorter-range Pershing IBs and handing them over to West Germany as a modern replacement for the old Pershing IAs.

2. Equal rates of destruction for both the U.S. and Soviet arsenals, "in equal percentages." The United States has proposed that only Soviet missiles be scrapped at first, until both sides reach the same numbers. "The U.S. side puts forward unequal terms of the order of the elimination of missiles," Akhromeyev charged today.

3. Equal rights for both sides in verifying that the missiles are being destroyed. The Soviet Union seeks the right to inspect acknowledged U.S. bases as well as areas where it suspects missiles are based or where it suspects missiles are in transport, Foreign Ministry arms control expert Viktor Karpov said here today.

Soviet negotiators in Geneva presented the new Soviet proposals today, and Vorontsov told journalists here that two months would be adequate time for the two sides to overcome their differences.

"The Soviet Union expects the U.S.A. to make concrete proposals and to agree to eliminate all warheads, including those it keeps at present for missiles belonging to other countries," Vorontsov said.

"Apparently," he added, "the next two months will be enough, considering that the two sides know well one another's positions. After this, if the treaty is finalized a possibility will open up for it to be signed at summit level."

Asked whether the Soviet Union envisaged a meeting between Soviet Foreign Minister Eduard Shevardnadze and Secretary of State George P. Shultz as part of the negotiating process, Vorontsov said that "the two sides in Geneva will have to proceed to serious work."

"They have experts on their staffs," he continued. "They can look into all the problems. If they do not succeed in this, then we will have to resort to our ministers."

Vorontsov also said that the new Gorbachev proposals are designed to enhance Asian security and to give an impetus to the process of making Asia a nuclear-free zone.

At the same time, Akhromeyev said that Moscow was dropping its insistence that the United States withdraw its aircraft from Japan as part of a "global double zero" pact.

He emphasized that the proposals were designed to meet halfway "the wishes of the countries of Asia, including Japan."