UNITED States President Bush delivered concrete evidence of his support for Soviet President Mikhail Gorbachev July 29. In a speech the first day of the summit, Mr. Bush announced that he would submit a trade agreement to the US Congress that would lead immediately to long-sought most favored nation trading status for the Soviets."The Soviet Union should become a full participant in the global economy, and the United States will support you in that effort," Bush said. As he did at the summit of seven Western leaders in London, Bush held out the possibility that more substantial aid would be forthcoming, but only after evidence of Soviet reform actions. "Progress rests on the pace of your reforms," he said, "on the speed with which you move from a system based on command and control to one based on supply and demand. As in Eastern Europe, our assistance will keep pace with your reform." Bush also tried to weave his way through the complicated tangle of Soviet internal politics. Referring to the proliferation of parties and political voices now erupting, Bush answered the question of where American support lies: "America stands with the forces of freedom and reform - wherever they are found." But during the first day of talks, it was already evident that this is far from a simple proposition. The US president started his day in the St. George's Hall in the Kremlin with the man he clearly knows - and likes - best, Mr. Gorbachev. But he ended his day of meetings by sitting down with Russian President Boris Yeltsin in his recently acquired Kremlin office. (The Moscow Bush won't see, Page 3.) Gorbachev is also trying to maintain a balance between preserving his authority and recognizing the new assertive role of the republics that make up the Union. He invited Mr. Yeltsin and Kazakhstan President Nursultan Nazarbayev, one of the more prominent republican figures, to join the talks with Bush and to lunch afterward. But Yeltsin pointedly did not appear, preferring instead to emphasize his own 45-minute meeting with Bush. The previous day Yeltsin signed a treaty with Lithuania, which treats the Baltic republic as an independent state. Yeltsin also devoted some of his remarks then to an attack on the Soviet Communist Party for its opposition to his recent decree banning all party cell organizations in factories and government offices. He mildly warned Gorbachev against issuing his own counterdecree, saying that "I think [Gorbachev] has enough common sense not to unleash a new war of laws and not to ... unbalance our relations." Yeltsin has also held up final agreement on a new treaty of union, which 9 of the 15 republics have basically agreed upon. Gorbachev has promoted this deal as a key sign of both emerging stability and an opening to serious economic reform. But Yeltsin has insisted that there be no federal tax system, with the republics having the power to tax and then passing funds on to the central government. In an apparent attempt to ease tensions and find agreement before the start of the summit, Gorbachev met with both Yeltsin and Nazarbayev, July 29. The independent Russian Information Agency reported that the three men reached agreement on the union treaty at 3 a.m. July 30, after seven and a half hours. According to various sources, the Russians won in their insistence that there be no direct tax collection by the federal government. But they propose to contribute to the central administration a sum equivalent to a percentage of their gross national product. The reported deal allows Gorbachev to present the Soviet Union as a unified nation. But it also reveals that he has conceded vast powers to Yeltsin and others for the sake of this image. The summit will "mark the end of a long era of mistrust, and a new beginning for our two nations," Bush dramatically ended his speech. He pointed to the example of Soviet cooperation in the Persian Gulf against the Iraqi regime. But he also called on the Soviets to remove "conflicts ... frozen in place by the long cold war." The US president called for solution of the Soviet-Japanese territorial dispute, for the cessation of Soviet military aid to Cuba, and for reduction of military spending. He offered US assistance for conversion of the Soviet defense industry to peaceful purposes. Bush carefully reiterated American support for the freedom of the Baltic republics of Latvia, Estonia, and Lithuania. The US has never recognized their annexation by the Soviet Union in 1940. Bush called for "good-faith negotiations" on their demand for independence, and "a clear and unqualified commitment to peaceful change."