Soviet President Mikhail Gorbachev arrived here last night for a four-day summit meeting with President Bush that Gorbachev said holds the promise of "the first major step to reduce strategic nuclear arms" and new understandings on European and other issues.

As Gorbachev flew to Washington, Bush was told by his top arms control negotiators that talks have advanced to the point that he and Gorbachev will be able to issue an "agreement in principle" that they have resolved the major outstanding issues of a landmark Strategic Arms Reduction Treaty (START).

They also are prepared to issue a second joint statement proposing objectives for broader and deeper cuts in a successor START II pact, according to a White House official.

The prospects of agreement are much dimmer on Germany and Lithuania, which were alluded to by Secretary of State James A. Baker III in his airport welcome to the Soviet leader. White House officials said Bush was advised that these difficult issues are not likely to be resolved here but that it may be possible to "set a direction" toward future accord.

Last night, Gorbachev summoned Soviet officials and journalists to the embassy for a meeting. Several participants said afterward that he opened the session by expressing high expectations for the summit, particularly in the arms control area. He then canvassed his guests for their assessment of the mood of the United States and the Bush administration, the participants said. They responded to Gorbachev that his stock was high in the United States and that Americans are expecting much of his visit, they said.

Earlier, Gorbachev and his wife, Raisa, stepped off his special Soviet airliner in the bright sunshine just before 7 p.m. after a state visit to Canada in which he took a hard line on the future of a united Germany and the independence-minded Baltic republics. After greeting U.S. and Soviet Embassy officials and walking down a red carpet, he was given a brief ceremonial welcome by Baker on the Andrews Air Force Base tarmac.

"The eyes of the world are on you and they are on President Bush," Baker said. "Together, our nations have the responsibility to leave behind not only the Cold War but also the conflicts that preceded it.

"To do that, we must see a Germany unified and Europe reconciled; we must reduce the danger of war by controlling nuclear, chemical and conventional arms, and by resolving regional conflicts," Baker declared. In a veiled reference to Gorbachev's troubles at home, he added, "And, of course, we want to see continued movement toward democracy and openness in the Soviet Union."

Gorbachev responded through his interpreter that "this summit stands out in its importance, first of all, for the promise it holds of the first major step to reduce strategic nuclear arms. Both sides have worked painstakingly together to prepare it."

In what seemed to be a reference to their Malta talks last December, cut short by a violent storm, Gorbachev said the current meetings are special because "this is the first time that the president of the United States and I will have enough time to reflect on and discuss, not only in a formal setting, but also in more informal surroundings, one on one, all questions either of us might have that fall within our responsibility."

The Gorbachevs, accompanied by Baker and his wife, Susan, and a 40-car caravan, traveled by motorcade to the Soviet Embassy on 16th Street NW, where they were to spend the night before going to the White House this morning for a formal arrival ceremony and the start of talks.

Gorbachev's arrival came 2 1/2 years since his previous trip to Washington at the invitation of President Ronald Reagan in December 1987, and two years to the week since Reagan traveled to Moscow for the last formal U.S.-Soviet summit.

Since then, all six Soviet allies in Eastern Europe moved toward abandoning communism, the Berlin Wall came down and Germany began moving rapidly toward unification after 45 years of division. Since Bush and Gorbachev met last December at Malta, nationalities disputes, secession crises, economic turmoil and political controversies have raised serious questions for the first time about the internal stability of the Soviet Union and about Gorbachev's leadership.

Gorbachev appeared older and grayer than in his last Washington appearance. He looked tired from his grueling trip and from a series of crises in the past few days, including panic buying in Moscow food stores and the election of a bitter rival, Boris Yeltsin, to a key political post.

White House officials said Bush and Gorbachev will meet in the Oval Office initially, joined only by one interpreter and one note-taker on each side, and then move into the Cabinet Room for expanded talks.

Joining Bush will be Vice President Quayle, Baker, Treasury Secretary Nicholas F. Brady, Defense Secretary Richard B. Cheney, White House Chief of Staff John H. Sununu, national security adviser Brent Scowcroft, deputy national security adviser Robert M. Gates and U.S. Ambassador to the Soviet Union Jack Matlock.

On the Soviet side, according to the White House, will be Foreign Minister Eduard Shevardnadze, Presidential Council and Politburo member Yevgeny Primakov, Deputy Prime Minister Yuri Maslyukov, presidential foreign affairs adviser Anatoli Chernayev, presidential military adviser Marshal Sergei Akhromeyev, Foreign Ministry U.S.A. Department chief Alexei Obukhov and Ambassador to the United States Alexander Bessmertnykh.

Bush devoted most of yesterday to private summit briefings with aides on economic issues, arms control and an overview, White House press secretary Marlin Fitzwater said. He said "very specific and meaningful agreements" would be approved by the leaders, including accords on grain sales, maritime transportation, study of oceans, exchange of cultural information, expanded civil aviation and the environment.

Fitzwater did not list a U.S.-Soviet trade agreement, which has been completed in full detail, as among those to be signed. A White House official said later the trade agreement "could still go either way" depending on the discussions.

The summit also will include signing of a long-disputed set of treaties on nuclear testing, and a chemical weapons accord. But the two leaders are expected to clash in their private talks on the future of Germany and on Lithuania's bid for independence.

Before Gorbachev arrived, Bush spoke by telephone with West German Chancellor Helmut Kohl. He also talked with Canadian Prime Minister Brian Mulroney after Gorbachev had departed Canada.

In Canada, Gorbachev expressed displeasure at what he described as Western efforts to dictate the future of Germany within the North Atlantic Treaty Organization but also suggested he might be bringing new ideas to Washington.

Fitzwater said earlier that Bush, in discussions with Gorbachev, would not propose direct limits on the size of a future German army. However, he said, the U.S. view is that future negotiations on conventional forces in Europe could consider further reductions in forces in a "central region." He added, "We are opposed to any proposal which would single out Germany for special limits."

Staff writer Gary Lee contributed to this report.