NEWS ANALYSIS : Iron Hand Tightens Its Grip on Baltic Regions : Groups loyal to Kremlin are moving to assume power. Progressives say outcome in republics will determine fate of democratic system.

The drum roll of gunfire in the Baltics has heralded the potential dictatorship that former Soviet Foreign Minister Eduard A. Shevardnadze had warned of.

“Committees of National Salvation,” overtly or covertly linked to hard-line Communist Party leaders and claiming the allegiance of army generals and elite Interior Ministry forces, are clamoring for the dissolution of the parliaments in the Baltic states.

In classic Marxist-Leninist fashion, the committees claim to speak for the workers and peasants of Estonia, Latvia and Lithuania, despite the Communist Party’s humiliating loss to pro-independence forces last spring in the first freely contested elections in half a century.

In Latvia, the Public Salvation Committee, which is openly headed by Communist Party Chief Alfreds Rubiks, proclaimed over the weekend that it was assuming power.

On Sunday night, elite “black beret” Soviet Interior Ministry troops, which a defector from the ranks claims act on orders from Rubiks’ party, stormed the republican Interior Ministry headquarters in Riga, Latvia’s capital.

Latvian police fought back, and at least five people were killed and 10 wounded in the gunfire. The assault, whose exact purpose remained unclear, was the latest proof of the vulnerability of the Baltic governments.

“All this is simply what the French call a coup d’etat,” a middle-ranking, Moscow-based Soviet official said when asked to analyze recent events in the Baltics.

Even in Estonia, the most tranquil of the Baltic republics so far, a “Coordinating Committee” is demanding that Prime Minister Edgar Savisaar’s Cabinet be replaced by a “Government of National Concord.”

So far, Soviet President Mikhail S. Gorbachev’s position is unclear, although he initially defended the military’s role in a clash in Lithuania a week earlier that left 14 people dead. On Tuesday, Gorbachev, apparently stung by a drumbeat of criticism, warned both the military and civilians to restrain themselves and called for an investigation into the bloody events in Vilnius, the capital of Lithuania, and Riga, the capital of Latvia.

Progressives in the Soviet Union believe that what happens in the Baltic republics will almost certainly determine the fate of the country’s fragile and still emerging democratic system.

The mayor of Leningrad, Anatoly A. Sobchak, called on “all democratic forces” to unite to safeguard the gains of the last few years under perestroika . The only way to stave off dictatorship, Sobchak said, was for the parliaments and city councils elected last year to remain in session and not give in to the bullying.

The Soviet army has used force against civilians before; in Tbilisi, Georgia, in April, 1989, soldiers killed 19 people, mostly women and the elderly, when clearing a central plaza of pro-independence demonstrators.

However, the military attacks this month in Vilnius that claimed 14 lives were qualitatively different. In the Lithuanian capital, “the first blow was struck against authorities who were freely elected by the people,” the weekly newspaper Moscow News commented.

Likewise, it was in Lithuania that the “Committee of National Salvation” ploy, first proposed for the Soviet Union as a whole by conservatives in late November, was pushed to the point of absurdity--and to its tragic extreme.

The Lithuanian committee, unheard of two weeks ago and still without identified members, is claiming for itself the same legitimacy as the Supreme Council, the republic’s elected parliament, as well as the presidency of Vytautas Landsbergis.

The pro-Moscow Lithuanian Communist Party, whose links with the shadowy committee are obvious despite the denials of Communist leaders, contends that “two centers of power” have arisen--the Supreme Council of the republic and the Committee of National Salvation.

Since neither side ostensibly can “fully master the situation,” the party argues, Gorbachev should impose direct presidential rule on Lithuania, effectively removing the elected government and installing his own administrators with the power to rule by decree.

However, after the brutality shown by Soviet troops in the Jan. 13 seizures of Lithuanian radio and television stations, which the Vilnius military commander said were executed on the committee’s request, no one now dares to be associated with it.

The man widely believed to be the leader of pro-Soviet forces in Lithuania, Vladislav Shved, an ethnic Slav, reportedly left on an official visit to France in the wake of the army action.

What comes next in the Baltics is the great riddle that everyone poses here.

The Roman Catholic archbishop of Vilnius, Julijonas Steponavicius, has theorized that the deaths of unarmed civilians at the hands of the army have forced the Committee of National Salvation to rethink its plans or at least to delay them.

“According to our information, on the night of the seizure of the television tower, there were also plans to seize the Supreme Council building and the Council of Ministers,” Audirus Butkevicius, the chief of Lithuania’s territorial guard, told The Times.

“All plans were coordinated with the center (Moscow), but the leaders of these operations had not foreseen that resistance by the people would be so great. They understood then that the Supreme Council would not be surrendered to them all that easily.”

The national salvation committees and the Baltic governments are now engaged in sort of a sitzkrieg , or sitting war, with no one knowing where the next blow will fall, or what move to take themselves.