UNITED States Secretary of State James Baker III left the Soviet Union yesterday proudly displaying some important trophies of his visit. In a series of announcements since last Thursday, the Soviet Union agreed to downgrade ties to Cuba and to end arms supplies to the Afghan government it has long backed.Along with Moscow's recognition of the independence of the three Baltic republics, "this removes three of the most contentious 'old-agenda' issues that have impeded and obstructed progress," Mr. Baker declared happily. But Soviet analysts and officials question the suggestion that these moves by Moscow are evidence of a change in Soviet foreign policy, a further liberalizing in the wake of the failed coup of last month. Rather, some suggest, it reflects the collapse in the last weeks of a Soviet central government strong enough to pursue a foreign policy of any kind. "Today it is evident that the Soviet Union, as a superpower possessed by messianic ideas, is finished," wrote Alexander Goltz in the Army daily Red Star last Friday. "We not only lack the means to support our ideas all over the world, we even lack the ideas themselves." The joint statement on Afghanistan had the appearance of mutuality, with the US also agreeing to cut off supplies to Afghan rebels and to encourage the formation of a new government through United Nations-supervised elections. When it came to Cuba, the Soviets called for reciprocity in the form of a US move to close its naval base at Guantanamo, Cuba. The Cuban government, which has denounced the Soviet decision, dismissed this as a meaningless gesture, and the Pentagon has already stated it has no inten tion of closing the base. Mr. Goltz, long a relatively conservative voice in a paper that traditionally upheld the might of the Soviet Union, questions whether what he dismisses as a "former state" can even have a foreign policy. "Foreign policy is being transferred to where there is power," he notes, namely the republics. When it comes to aid to Cuba or Afghanistan, for example, "I am sure that no sovereign republic will spend money in support of such regimes." As for a Soviet role in regional conflicts, such as Cambodia or the Middle East, "Let's be frank, in a situation of semi-decay, our participation in settling of these conflicts has only a nominal character," Red Star's commentator writes. The Soviet role in the past largely consisted of being a major military power, especially a supplier of weapons, Goltz points out, "but I seriously doubt that Russia or the Ukraine will finance such participation in the future." On the surface, a new structure of cooperation is being created between the republics and the Soviet Foreign Ministry, now headed by newspaper-editor-turned-diplomat Boris Pankin, the only Soviet ambassador to openly oppose the attempted putsch. Last Friday, Mr. Pankin held a meeting with the foreign ministers or their deputies from nine republics, including the four Central Asian republics, Kazakhstan, Azerbaijan, Armenia, Moldavia, and Russia. Byelorussia's minister missed the meeting for what he called technical reasons. Aside from the three Baltic republics and Georgia, the noticeable absentee was the Ukraine. According to Soviet press reports, the ministers agreed to form a Council of Foreign Ministers, which will direct the entire Soviet diplomatic service. The republics demanded that their personnel partially replace existing trade and diplomatic representatives in embassies around the world and demanded a share of the hard-currency funds now controlled by the Foreign Ministry. As for who represents the country, Pankin told the Soviet news agency Interfax that all the republics should be seated in the UN but that the Soviet Union will act as a single state in institutions such as the UN Security Council and the International Monetary Fund. But how this might work in practice is far from clear. All the republics supposedly agree, for example, that there should be centralized control of nuclear weapons. When Baker proposed talks on getting rid of short-range nuclear weapons - artillery and rockets - he did so in a meeting with the Soviet Armed Forces Chief of Staff Vladimir Lobov. But Russian President Boris Yeltsin had already made a proposal to remove all these weapons earlier last week. A subtle competition is also developing between the Russian republic and the nominal central government over access to foreign aid. Gorbachev envoy Vadim Medvedev flew off to South Korea yesterday. The main topic on his agenda is to resecure a South Korean pledge to provide $3 billion in credits over the next few years. But Russian leader Yeltsin sent a letter to Korean President Roh Tae Woo last Thursday seeking direct ties between Russia and South Korea and stating his desire to visit Korea. A much better indication of the reality of who runs foreign policy came during the visit last week to Japan of Ruslan Khasbulatov, the acting chairman of the Russian republic's Parliament. Soviet-Japanese relations have been deadlocked for at least 20 years over the dispute over ownership of islands in the Southern Kuriles, which the Soviet Union seized from Japan at the close of World War II. Without return of those islands, Japan refuses to sign a formal peace treaty ending the war or to provide large-scale economic assistance. A visit to Japan last April by Soviet President Mikhail Gorbachev, the first ever by a Soviet leader, failed to make a breakthrough on this issue. Mr. Khasbulatov, who carried with him a letter from Mr. Yeltsin to Japanese Premier Toshiki Kaifu, bluntly told the Japanese that if they want the islands back, they had to come to the Russian government. "The new situation is such that all relations with Japan can be forged only on the basis of talks with Russia," Khasbulatov told Soviet reporters in Tokyo at the close of his visit. "This is not a claim, this is a reality." The Russian politician also made it clear that Russia expects the return for its cooperation to be massive economic aid - $8 billion to $15 billion he told the Soviet journalists - coming to Russia itself. With such a show of Japanese sincerity, he indicated the Russian government was ready to move quickly to negotiate an end to the island dispute along the lines of a five-stage plan proposed by Yeltsin during a trip to Japan last year - and ignored by Tokyo authorities at the time. Khasbulatov found the Japanese, like many Western governments, slow to understand the new reality. "I realized that Japan still looks to the Soviet Union, at Gorbachev," he said, according to a Tass report. "They display some inertia, visualizing the world as it was before the coup attempt in Moscow." Khasubulatov also had some words of warning for those in Moscow who do not themselves understand that Russia will now be making foreign policy with Japan. According to a report in the daily Izvestia, he told a Tokyo press conference that if the new foreign minister doesn't understand this, "we will replace him." Later, speaking privately to the Soviet Embassy staff, he recounted telling the Soviet Ambassador to Japan "that he will stay as long as he is personally loyal to the president, Parliament, and l eadership of Russia."