MOSCOW, SEPT. 26 -- They climbed trees to see him and dropped down on their knees to kiss his coat. Russia is in the midst of a tense political confrontation, but in Red Square today there was only excitement: Mstislav Rostropovich, beloved here as few others, was back on his native soil to conduct an open-air concert with Washington's National Symphony Orchestra.

Under sunny skies but with temperatures so close to freezing that orchestra members were wearing gloves, parkas and fur hats, tens of thousands of Russians crammed shoulder-to-shoulder in the historic square where Russian leaders for centuries have demonstrated their might.

Today, music held sway as acclaimed cellist and conductor Rostropovich, the orchestra and the Choral Arts Society of Washington performed the work of two great Russian composers, Sergei Prokofiev and Peter Ilich Tchaikovsky, who died on this date 100 years ago. But, as always here, politics was not far behind.

Russian President Boris Yeltsin, whom Rostropovich has vocally supported in his power struggle with the anti-reform parliament, showed up for the concert, appearing confident and boisterous as he walked from his nearby Kremlin office with Defense Minister Pavel Grachev and other aides. Large crowds applauded him and yelled support for Yeltsin's decision on Tuesday to disband parliament and set December elections for a new legislature.

Yeltsin's upbeat mood contrasted sharply with the angry atmosphere around the barricaded parliament building, where Vice President Alexander Rutskoi, appointed Russia's acting president by hard-line lawmakers who voted to strip Yeltsin of the presidency, continued to hunker down.

Tension remained high there as several thousand people, brandishing red Soviet flags, anti-Yeltsin placards and what appeared to be molotov cocktails, continued to "defend" the building against possible assaults by Interior Ministry forces that have cordoned off the area. Parliament Speaker Ruslan Khasbulatov said his forces were prepared to sit indefinitely inside the building, which is without electricity, water and telephone service.

Momentum appeared to be building to end the standoff as more attention was being paid to a proposal to schedule simultaneous elections for parliament and president.

{Russian Foreign Minister Andrei Kozyrev, appearing today on the NBC-TV program "Meet the Press," said that if there is a "growing mood" in the country, Yeltsin might compromise on his plan to hold parliamentary elections in December and a presidential election in June, the Associated Press reported.

{In Moscow, at least 10,000 demonstrators carrying Russian flags and placards bearing such slogans as "Elections Are the Will of the People" and "Boris, You're Right Again" marched down Tverskaya Street -- Gorky Street in Soviet times -- in the biggest demonstration of support for the president since he disbanded parliament, the AP reported.}

Like Yeltsin, many of those attending today's concert seemed delighted to have a chance to focus their thoughts on something other than the political crisis. However, when cannons exploded for the finale of Tchaikovsky's "1812 Overture," many people jumped, and several people yelled in jest: "A coup!" Grachev, in the VIP section with Yeltsin, may have been thinking the same thing, for when the first cannon fired, he whispered something into his boss's ear that made Yeltsin chortle.

For members of the National Symphony and Choral Society, the scene taking place in the enormous expanse of Red Square, with the domes of St. Basil's towering above them, was overwhelming.

"Slava {Rostropovich} told us before we came here that he wanted to give us a gift that we would always remember," said Suzy Waldo, a Choral Society member, as she watched Yeltsin disappear through a huge gate into the Kremlin. "And this we will always remember."

Most Russians who streamed into Red Square for several hours leading up to the concert did not appear to know that Yeltsin had been there. It was Rostropovich they had come to see and music they had come to hear. The crowds were so large -- five to 10 times bigger than any gathering on behalf of either side in the political crisis -- that at times it was impossible to move, and some younger listeners climbed trees for a better view.

"We had heard about this orchestra, and we wanted to hear it," said Margaret Klimenko, 58, who came early to find a good spot. "And our Rostropovich, we haven't seen him in a long time, only on television."

Klimenko, like many of the older people in the crowd, recalled having seen Rostropovich, 65, play in concert in the 1960s and 1970s before he and his wife left the country in 1974 and Soviet authorities stripped them of their citizenship four years later. He became music director of the National Symphony in 1977, a post he is set to leave at the end of the 1993-94 season in June, after which he will become lifetime conductor laureate.

Rostropovich made an emotional return to Russia, then the Soviet Union, with the orchestra three years ago when Soviet leader Mikhail Gorbachev agreed to restore his citizenship. He has been back several times since.

For Rostropovich, however, this tour had a special significance. This is his 17th and last season with the National Symphony, and it should have opened earlier this month in Washington. But Opera House musicians are on strike at the Kennedy Center and orchestra musicians will not cross their picket line to play. As a result, Rostropovich opened his final season in the country of his birth and in the city where he made his mark as a great cellist and conductor. In a clear sign of his importance here, today's Red Square concert was the lead item on national television news.

Since arriving here, Rostropovich has come out strongly again for Yeltsin, saying during a news conference two days ago, "I count his every second to be precious for Russia."

One of the major reasons Rostropovich was deprived of his citizenship was the defense -- and shelter -- he provided to a famous friend -- dissident and writer Alexander Solzhenitsyn, whom Soviet authorities expelled for excoriating the regime and exposing life in its forced labor camps, or gulags, in his books.

Thus it was with a delicious sense of irony and revenge for many that Rostropovich returned for this two-week tour with Solzhenitsyn's son, Ignat, as a piano soloist. Ignat, 20, was an infant when his parents were forced to leave Moscow. He was reared in Vermont as a U.S. citizen.

Rostropovich said he selected the music of Prokofiev and Tchaikovsky for today's concert because they are "the two greatest Russian composers" and specifically chose the "1812 Overture" and Prokofiev's "Alexander Nevsky" cantata as the finale to remind Russians during such difficult times that they are a great people with a great culture.

For many Russians attending the concert, this message clearly was well-received. "I have this wonderful feeling being here," said Valentina Sohina, 57, the head of a local nursery school, as bells pealed during the "1812 Overture." "Our country has had so many difficulties, but it is still a great country with so many very talented people. And if we try, we can survive our troubles."

For a few hours last week, it was not clear whether these concerts would take place. As the orchestra was preparing to leave Washington on Tuesday, news came of Yeltsin's decree disbanding parliament and the lawmakers' vote to oust Yelstin. Many were worried about violence or about tanks rolling again, as they did during the abortive Kremlin coup in August 1991.

For Rostropovich, who was here during those tension-filled days, the new political crisis was no reason to cancel the trip. But he said he was not sure his orchestra members would feel as he did. "I would have left no matter what happened," he said. "I was only worried about whether I would find the symphony orchestra at the airport when I got there. Americans are not used to taking part in military actions."

But all the musicians showed up, and orchestra Executive Director Stephen Klein said he realized everything would be fine at Moscow's international airport when well-wishers and reporters met them. "We immediately asked what was happening, and they said that they were so excited we had arrived."