MOSCOW — AS Western ambassadors begin arriving in the Baltic states, what was once a far-out scenario has become a reality - the breakup of the Soviet empire.The Romanian-populated republic of Moldavia joined the three Baltic states of Estonia, Latvia, and Lithuania Aug. 27 in declaring its independence from the Soviet Union. Even the staid republic of Byelorussia, where nationalist sentiments are not strongly entrenched, has rushed to declare its sovereignty. In the halls of the Soviet parliament, which began an emergency session on Aug. 26, the talk is whether the Soviet Union will survive as a unified state. "The center is dead," Armenian President Levon Ter-Petrosyan happily proclaimed. (Interview, Page 3.) Asked by the news agency Interfax about a proposal that he resume his post as Soviet foreign minister, Eduard Shevardnadze retorted: "When there is no USSR, what do you need a minister for?" In response to Soviet President Mikhail Gorbachev's call for new Soviet elections, Leningrad deputy Sergei Tsyplyaev said, "Of course we must organize new elections, but the question is in what country to organize them.... In a few months, we will have fully destroyed the previous union and have 15 independent republics, or more." These developments are hailed by some as a logical outcome of the fall of the Communist state since the failed hard-line coup last week. But increasingly, even among supporters of the democratic movement, these events are greeted with apprehension. On the part of the non-Russian republics, voices are rising against Russian domination of any future union. On the part of Russia and among a section of the democrats, there is the concern that the Communists in such places as the Central Asian republics, the Ukraine, and Byelorussia, are now using nationalism to preserve the old system there. Russian domination is already a political reality. What remains of the Soviet central government is being taken over by the Russian Federation government of Boris Yeltsin, with Russian Premier Ivan Silayev now functioning as Soviet premier and appointing members of his Cabinet to take over all major Soviet ministries. Kazakhstan President Nursultan Nazarbayev showed these anti-Russian sentiments when he spoke to reporters at the Soviet parliament Aug. 26. "The president and prime minister are Russian, and now we hear that they may agree that the vice president be from Central Asia," he said, adding sarcastically, "Well, thank you very much." Both Mr. Nazarbayev and Ukrainian deputy Yuri Shcherbak presented a vision of a new union as a far looser confederation than previously envisaged. Nazarbayev wants to relegate a union government to protecting borders, but with defense, including nuclear-weapons control, jointly run by republics. Each republic would have its own army, delegating some men to a joint force. Mr. Shcherbak called for scrapping the proposed new treaty of union entirely, putting in its place a "Euro-Asian economic community" and a military-political structure similar to NATO. The tensions between Russia and these two large neighbors, both of which have considerable Russian minorities, took an additional leap when Yeltsin's spokesman issued a statement Aug. 26, warning that if the republics pull out of the union, "the Russian Federation retains the right to raise the question of revising borders." The statement exempted the Baltic states, with whom Russia has signed treaties. But the spokesman explained that the statement referred mainly to northern Kazakhstan and to the Donbass region and the Crimea in Ukraine, all Russian-populated areas. "If these republics enter the [renewed] union with Russia it is not a problem," spokesman Pavel Voshchanov told reporters. "But if they go, we must take care of the population that lives there and not forget that these lands were settled by Russians." Russian deputy Oleg Rumantsyev, a liberal leader, echoes these sentiments. "If we are provoked toward civil war by irresponsible leaders of the republics," he says, "then we will respond from a position of force and self-confidence." Russian Vice President Alexander Rutskoi called for the union to be preserved for both economic and military reasons. In a press conference, he warned the breakup of the union could encourage "the rebirth of the Russian empire" by leaving all the strategic nuclear weapons and major military forces in Russia. Behind such talk, some Soviet observers say, is the fear Russia will be left in a union solely of itself and the Muslim republics of Central Asia. For this reason, the stance of the Ukraine is considered the key to the future of any union. Without the Ukraine, comments Soviet analyst Sergei Blagovolin, "it will be a terrible cocktail of Russia and the Central Asian republics. In this case, it will be better for us to be alone." Leading democrats such as Leningrad Mayor Anatoli Sobchak and Moscow Mayor Gavriil Popov have emerged as strong advocates of maintaining the union and central administration. They warn that the Communist Party governments that remain in power in Central Asia, Byelorussia, and the Ukraine are now using "national communism" to survive. These democrats "proceed from the apprehension that secession of certain republics from the USSR will lead to the preservation of Communist regimes," Vera Kuznitzsova commented in the independent newspaper Nezavisimaya Gazeta Aug. 27. Such concerns are shared by non-Communists in those republics. "The Communists need an independent Byelorussia not for the interests of Byelorussia itself," liberal Byelorussian deputy Aleksander Adamovich told the Monitor. "They need it to preserve their own and the party's power." He raised the specter of a Communist Byelorussia that would have nuclear capacity and enter into a territorial, ideological confrontation with Russia. The rapid decision of the Ukrainian parliament, where the Communists still dominate, to declare independence last week is also questioned by Rukh, the coalition of democratic and nationalist forces in the republic. Rukh leader Ivan Drach dismissed this in Nezavisimaya Aug. 27, as a "cunning maneuver of the [regime] to preserve itself and the local party structures." But as a result, "the Ukrainian supporters of independence face a rather dramatic option: either to join the democratic empire or to begin with national Communist independence," he said. The only alternative to breakup seems to be a revision of the draft treaty of union, which would make the Soviet Union a full confederation, with an economic union at its core.