Among Russia’s Neighbors--Fear : Commonwealth: Former Soviet lands unite behind Yeltsin, terrified of a nationalistic alternative.

When Oleksandr Kovtunenko heard Sunday that Russian President Boris N. Yeltsin might be impeached, the young Ukrainian businessman decided to buy a gun, “the biggest I could find,” in case of an invasion by imperialists from Moscow.

“I will fight against anyone to defend Ukraine,” Kovtunenko said, nervously sipping coffee in a Kiev cafe.

Serhij Nechitailo, his business partner, had a safer idea. A plane ticket to the West, he suggested, might be a better bargain.

Neither man has acted yet, but their discussion had an edge of urgency, punctuated by references to some bloody military skirmishes last week between Russia and Georgia along a slice of the Black Sea coastline.

The talk in Kiev these days, as in other outlying capitals of the former Soviet Union, is tinged with fear that Yeltsin’s defeat in a power struggle with his hard-line, nationalist Parliament might give free rein to Russia’s ancient instinct to dominate its neighbors.

Leaders of nearly all the newly independent states--including Ukraine and Georgia, whose relations with Moscow are most strained at the moment--have sent messages of support for Yeltsin in the faint hope that their words will somehow help.

“We are praying day and night for Yeltsin to stay in power,” said Deputy Prime Minister Boris Shikhmuradov of Turkmenistan. “Any of those who might come after him, all of them have an ax in their hand.”

The 15 Soviet republics went their separate ways after an August, 1991, coup attempt failed to reimpose hard-line Communist rule. Most of their leaders supported Yeltsin as he defied the coup and have worked personally with him in the loose alliance known as the Commonwealth of Independent States.

Now they are watching Moscow more closely than at any other time since the coup.

Under Yeltsin, Russia has managed, most of the time, to keep peace along its frontiers while adjusting painfully to the breakup of its empire. But as economic hardship pulls down Yeltsin’s popularity, rising nationalism is pushing Moscow to become more aggressive in defense of Russian minorities and military installations beyond its borders. A revived Communist Party, meanwhile, is demanding restoration of the Soviet Union.

The most dramatic flare-up came last week when Russian warplanes joined a separatist offensive against Georgian positions in the breakaway province of Abkhazia on Georgia’s Black Sea coast, where the Russians are trying to hold onto air bases. Georgia shot down a Russian air force jet Friday, killing the pilot.

Yet two days later, when lawmakers in Moscow started the wheels of impeachment against Yeltsin, Georgian leader Eduard A. Shevardnadze spoke out in his defense.

Shevardnadze, loathed by hard-liners as the Soviet foreign minister who “lost” Eastern Europe, said that only Yeltsin could protect him against the Russian army. The Russian leader is losing control of his military as it resists local pressure to withdraw bases from Georgia, Shevardnadze said.

“There is a smell of civil war in Moscow,” said Shevardnadze, who warned prophetically against the 1991 coup there. “If there is an explosion in Russia, none of the former Soviet republics would escape the blast.”

Georgians with long memories agreed.

“God help us if there is a coup in Moscow,” said an 83-year-old Georgian woman shopping for bread in the capital of Tbilisi who identified herself only as Daredzhan. She said the Red Army executed her father when it crushed Georgia’s independence in 1921, four years after the Bolshevik takeover of Russia. “There will be terror, murder here. It will be a nightmare. There will be tanks in the streets again,” she said.

Ukraine, the richest country in the Commonwealth after Russia, has been locked in endless disputes with Yeltsin’s government over control of 176 strategic nuclear missiles on Ukrainian soil and of the Soviet navy’s Black Sea Fleet, as well as over prices for Russian natural gas.

But President Leonid Kravchuk this week threw his support behind the “popularly elected president” in Moscow and Yeltsin’s call for a popular referendum on his rule.

The reasons are obvious. Russian Vice President Alexander V. Rutskoi, who has turned against Yeltsin and stands to become president if he goes, is despised here for visiting Crimea as if it were part of Russia. And the legislature now contemplating Yeltsin’s impeachment has voted to question the legality of the Soviet Union’s transfer of Crimea to Ukraine’s jurisdiction in 1954.

Asked to choose between Yeltsin and Rutskoi, Dmytro Pavlychko, head of the Ukrainian Parliament’s foreign relations committee, said: “Yeltsin is no saint. Like every Russian, he has not been cleansed of chauvinism. . . . But with Yeltsin, we’re less likely to have a war.”

In the Baltic nations, the first to break with Soviet rule, many say they would simply make themselves ungovernable if Moscow tried to take over again.

“I don’t think they’d want us back,” said Jaak Ahelit, 33, drummer for Compromise Blue, a popular Estonian rock band. “It would be more trouble than it would be worth.”

Estonian officials are not taking any chances, however. They recently drew up contingency plans to defend their tiny country in the event that turmoil in Russia spills over the border.

The presidents of Estonia, Latvia and Lithuania have voiced support for Yeltsin, as have leaders of all but three other former republics--Azerbaijan, Tajikistan and Belarus, which remain neutral.

These statements would seem to count for little in tipping the balance of power in Russia. But their importance to Yeltsin was underscored last week when Ruslan I. Khasbulatov, Speaker of the Russian Parliament, traveled to Kazakhstan, Belarus and Ukraine, trying to project himself as an equally important Commonwealth figure.

His visit, on the heels of a detailed Yeltsin proposal for strengthening the Commonwealth, did not go down well here.

“He was testing his support here,” said Pavlychko, who took part in Khasbulatov’s meeting with the Ukrainian leader. “I think he was disappointed.”

Mycio, a special correspondent, reported from Kiev and Times staff writer Boudreaux from Moscow. Special correspondents Lori Cidylo in Tblisi, Georgia, and Matt Bivens in St. Petersburg, Russia, also contributed to this report.