NEW YORK, SEPT. 27 -- Secretary of State James A. Baker III and Soviet Foreign Minister Eduard Shevardnadze today resolved several major obstacles to a treaty limiting conventional military forces in Europe and narrowed their differences over aircraft, one of the most difficult remaining issues, participants said.

After a day of intensive talks on the issue of conventional, or non-nuclear, forces, Shevardnadze said that there had been "quite substantial progress" and that both sides would consult with their respective alliances, the Warsaw Pact and the North Atlantic Treaty Organization. The treaty is to be formally consummated between the alliances, but, following the changes in Europe in the last year, both alliances have become less relevant. The Warsaw Pact has all but crumbled as a military organization, and NATO has been searching for a new, more political mission.

But U.S. negotiators said they believe the conventional forces treaty is still relevant because it would lock in permanent arms reductions made possible by the easing of tensions in the last year.

Both the United States and the Soviet Union have been under increasing pressure to complete the treaty before the 35-nation European summit opens in Paris in eight weeks. The treaty is supposed to be signed at the summit, which is being planned as a celebration of European harmony and the launching of new institutions for cooperation.

In recent months, negotiations on the treaty have been lagging, and U.S. officials reiterated again today they would not participate in the summit without first completing the treaty. Such talk has made European leaders nervous, however. A senior French official said it would be foolish to postpone a meeting with "so much at stake" because "some little nut or bolt is not screwed in place."

Officials familiar with the talks said substantive hurdles remain, particularly on verification and destruction of weapons, but they were encouraged by the progress made today. "The Soviets came here ready to deal," said a U.S. official familiar with the negotiations. A senior State Department official, referring to a feeling of frustration among U.S. officials that the Soviet military was slowing down the negotiations, said, "On the Soviet side, it helps to have the political leadership involved."

This reference to Shevardnadze follows the Soviet minister's speech to the U.N. General Assembly on Tuesday in which he criticized the Soviet military buildup. "We in the Soviet Union have had the unfortunate experience of building up a redundant defense capability," he said. "It is now common knowledge that militarization is wasteful for any country and can be ruinous when taken to extremes."

Baker and Shevardnadze devoted two hours of talks today exclusively to conventional forces issues and did not take up the strategic arms treaty, for which negotiations have also been stalled in recent months. They agreed to hold yet another meeting in the next few days.

Baker said he and Shevardnadze worked out a "possible agreement" on a rule in the conventional forces treaty that no single nation may have more than a stipulated percentage of the total tanks, artillery and other weapons allowed to remain in the region. This is known as the "sufficiency rule" and is designed to make sure than one country does not dominate the forces of East or West. The United States had previously sought a maximum of 30 percent of the forces for any one country and the Soviet position was 40 percent. Officials would not provide details about the compromise.

Similarly, Baker and Shevardnadze resolved differences on the total number of weapons allowed in various zones in Europe outlined by the treaty. The zones are to be set up under the treaty to avoid concentrations of troops and weapons in any one area.

Baker told reporters "we made some progress today on aircraft," but officials cautioned that on this issue they remained short of agreement. Both the limits of aircraft and definitions of what kinds will be covered by the agreement are still at issue, officials said. The Soviets are seeking to exclude from the treaty certain planes, such as combat-ready trainers and some land-based naval aircraft, that the West is seeking to limit. The United States, on the other hand, insists that carrier-based aircraft be excluded from the treaty limits.

Still to be resolved are disagreements over verification involving what kinds of inspections will be permitted. A U.S.-Soviet working group on the topic was scheduled to begin talks tonight on this subject, which American officials said is vital to the prospects for ratification of a treaty and also to support the argument that, despite the changes in Europe, the treaty is still needed to lock in the withdrawal of forces.

Another disagreement is over destruction of weapons. The Soviets have said they want to convert tanks to peaceful uses. U.S. officials have argued that the tanks "don't make good firetrucks," as one put it, and should be destroyed.