WHEN right-wing nationalists rallied in Moscow last week, shouting ''the war against Orthodox Serbs is a war against Russia, against the Slavonic peoples,'' fewer than 200 Muscovites bothered to listen.
But even the most West-leaning Russians tend to be strongly pro-Serb, and they are increasingly baffled and chagrined by what they see as American one-sidedness in the Balkan war.
This weekend's Croat offensive against Serbian forces in the Krajina region of eastern Croatia - and the tacit approval of the US - is sharpening ancient cultural divisions and creating new dismay among Russians.
By taking such an unbalanced, anti-Serb position, the US has let the Balkans deteriorate into a place where ''each major power has its own clients,'' says Vladimir Averchev, a moderate parliamentary deputy on the international affairs committee.
This is why Russian President Boris Yeltsin suggested yesterday that he is trying to put Russia at the center of brokering the Balkan conflict. He invited the Serbian and Croatian presidents to Moscow for peace talks.
While he did not explicitly criticize Croatia's attack, a foreign ministry official said Russia might seek United Nations sanctions against Croatia, according to the Interfax news agency.
Further, if the United States Congress decides to unilaterally lift the arms embargo from the Bosnian Muslims over President Clinton's objections, then the Russian Duma (lower house of parliament), Mr. Averchev worries, may respond by trying to unilaterally lift its economic embargo on the Serbs.
Even if Mr. Yeltsin were to approve such a measure, it would probably not impact the war in the Balkans, Averchev says. But such a confrontation of sympathies between the US and Russia would be ''very dangerous'' to relations between the two powers.
Croatia's reentry into the battle came just days after the US Senate and House passed a resolution to lift the arms embargo on Bosnian Muslims, a move Russian diplomats strongly criticized.
While Americans might see these moves as ways of containing or rebutting Serbian aggression, Russians see both the lifting of the arms embargo and the Croatian offensive as so much more gasoline on the devastating fires of Balkan violence.
Behind the practical considerations are deeper cultural sympathies and suspicions. Perhaps on no issue today do Americans and Russians understand each other less than on the Balkans.
Russians tend to see a strong imbalance in the Western view of the Balkans. NATO forces will bomb the Serbs for violating ''safe areas,'' for example, but not Muslims for using safe areas as military staging grounds, says Akop Nazaretyan, author of ''Aggression, Morals, and Crises in the Development of World Cultures.''
''The whole logic impels Russians to defend the Serbs,'' says Dr. Nazaretyan, a Moscow State University professor. Even Russians with very pro-American views ''acknowledge Western bias and arbitrariness'' against Serbs.
Russians hold a long sense of brotherhood with Serbia. This sometimes swells into an ethnic nationalist movement such as Pan-Slavism, but Russians are selective about their Slavic fellowship. Serbs are the closest cousins to the Russians politically, culturally, and religiously.
Popular Russian support for Serbia drew thousands of Russian volunteers to the Serbian army against Turkey in 1877. And Russia entered World War I as Serbia's protector against Austria and Germany, again with sympathy for the Serbs leading the way.
A bulwark against Islam
The Serb-Russian bond is more than an ethnic phenomenon. The Croats and the Bosnian Muslims are just as Slavic as the Serbs, but the Croats are Roman Catholic, and many Bosnians descend from ancestors converted to Islam by Turkish conquerors centuries ago. The Serbs write Serbo-Croatian in the same Cyrillic alphabet as Russians, while Croats traditionally write the same language in the Latin script of the West.
Radical Russian nationalists now tend to see the Serbs as the embattled forward post as Islam and the US-led West try to expand deeper into Slavic territory.
As Russian opinion is further inflamed by perceived Western bias against Serbs, the benefits, Averchev says, goes to the nationalists. Vladimir Zhirinovsky, the Duma deputy and ultranationalist, used the Croatian attack to launch an offensive of his own on Friday: ''If we had another president, the Russian Army would already be there, and no one would be able to touch the Serbs.''