The United States and the Soviet Union announced on Saturday that they had settled their differences on a far-reaching treaty reducing conventional arms in Europe and that they were preparing for a summit meeting, possibly by the end of June, between President Bush and President Mikhail S. Gorbachev.

After a long meeting with Soviet Foreign Minister Alexander A. Bessmertnykh, U.S. Secretary of State James A. Baker III said that Saturday's agreement would allow the two sides to step up negotiations on a new strategic arms-reduction accord, which is scheduled to be signed at the summit meeting.Baker said that the two leaders hoped to meet in Moscow to sign the new treaty "at the earliest possible date," but he refused to speculate when the summit meeting might be held.

"We had hoped for it in the first half of 1991," he said. "I can't say we can meet that schedule, but we will work to that end."

Bush, in a commencement speech at the United States Military Academy, in West Point, N.Y., hailed the settlement for "clearing the way for an important step toward a superpower summit."

The summit meeting had originally been planned for early this year but was postponed at Gorbachev's request after strenuous American criticism of a Soviet crackdown against the Baltic republics. Progress toward a strategic-arms treaty was also slowed by disagreements over the conventional-weapons treaty.

That treaty, which was hailed as the most sweeping disarmament accord ever when it was signed at a major East-West summit meeting in Paris in November, establishes limits on the number of tanks, armored personnel carriers, artillery pieces, combat aircraft, and combat helicopters that can be held by NATO and Warsaw Pact nations.

In practice, it meant that the Soviet Union would be required to destroy thousands of tanks and other weapons and would lose its traditional huge superiority in conventional weapons in an area stretching from the Atlantic to the Ural mountains.

But soon after it was signed, disagreement arose over Moscow's effort to exclude weapons controlled by its coastal defense, strategic missile, and naval infantry forces from ceilings imposed by the treaty. The Bush administration responded by delaying a request for congressional ratification of the treaty.

After Saturday's agreement, the timing of the summit meeting appears to depend on early conclusion of the strategic-arms treaty.

"We're thinking of having the team leaders go to Geneva and resume discussions on a more intensive basis than in recent months," Baker said.

During their three-and-a-half-hour meeting on Saturday, Baker and Bessmertnykh, who came to Lisbon to witness the signing on Friday of an agreement to end Angola's civil war, also discussed Middle East peace efforts and both men later met separately with Syrian Foreign Minister Farouk Sharaa.

Baker told reporters that he had delivered "a very detailed letter" from Bush to President Hafez Assad of Syria and had invited Sharaa to Lisbon so that he could "go over the letter in person." But he refused to divulge its contents.

Sharaa said that Washington and Damascus would continue their contacts about a possible Mideast peace conference, but also gave no details.

Asked if his trip had been worthwhile, he said: "Yes, I think so." Asked if it had moved forward the peace process, he said, "I hope so."