Chanting "Russia out of Afghnistan" and "Death to Brezhnev," a saddened but determined band of 270 Afghan patriots marched yesterday through the windy, snowswept streets of Washington to protest the Soviet military invasion of their mountainous homeland half a world away.

"How can you fight Russian bombers and tanks with a few guns and bare hands?" wondered MohammadHanif Sadiq, 43, Arlington taxi driver who, for the last three years, has been struggling to bring his wife and three children to America. "But bare hands are all we have -- we will use them.

"We will die for our freedom," he said, shivering in the toe-numbing cold at 16th and K streets NW, where D.C. police pushed back the angry marchers with nightsticks a block and a half from the Russian Embassy on 16th Street.

An Afghan ripped up a red Soviet flag and marchers stomped on it, frustrated that police would not allow a small child to hand-deliver their demands -- that 50,000 Soviet Troops withdraw from their country immediately -- to the steps of the Russian Embassy.

"The law says, 'Nobody within 500 feet of an embassy -- you're over the 500-foot mark," said a police officer, as marchers with stick beat an effigy symbolizing "a human being under Soviet domination -- they cut your tongue out and put your soul in prison," as one put it.

"Today, every Afghan hear is crying," said Sadiq, a former development project administrator who left his homeland because he "could smell the Russians coming. Freedom is a slogan written in the heart of every Afghan."

They were struggling students, dishwashers and waiters, doctors and hairdressers, teachers and former government officials-turned taxi drivers who had fled Afghanistan's earlier Communist regimes for America. And they wrapped themselves in coats and blankets against weather that made many homesick for the rugged moonscapes and bitter winters of their land.

But Russia's Christmas Eve invasion of Afghanistan has thrust that little-known land onto the center stage of world attention. And now Afghans, whose country has survived earlier invasions by Alexander the Great, Genghis Khan, the British, the Indians and the Russians, find a world suddenly ready to listen.

"Just call me 'Abdul,'" said a 27-year-old Afghan immigrant as he drew a white wool scarf about a green tweed overcoat and shivered outside the Islamic Center on Massachusetts Avenue. "I can't give my last name because I am afraid for my family in Kabul."

He stood amid a group of fellow countrymen who had bundled up wives and children to march up Connecticut Avenue to join other Moslems for a second march that swelled their ranks to 500.

Abdul said he last heard from his father, an exporter, one month ago, "but that's obsolete now." Three brothers have been in and out of jail since 1978, when Communist leader Nur Mohammed Taraki toppled Mohammed Daoud, who had toppled King Mohammed Zahir Shah. Now, two leaders later, Abdul has no idea if his family is dead or alive.

"Everyone you see here is lost," said Abdul, one of an estimated 300 Afghans in the Washington area. Some 2,000 Afghans reside permanently in the United States, the Afghanistan Embassy estimates, but no one seems to know for sure.

"They have nothing to look back on. They can no longer lean on their families, their culture, their heritage, their values. And the sad part is that thousands of Afghans will die -- just simple people living in the mountains who won't know why they're dying -- because of what could become a giant sturggle between two super powers," he said.

"They're not Afghans," shouted Gina Abawi, 18, a Virginia hairdresser who left Afghanistan two years ago, as she pointed to the Moslem marchers lining up beneath placards outside the Islamic Center. "They're Iranians."

Indeed, as hundreds of Iranian students prepared to join the second afternoon protest, many Afghans became angry at the thought that they might be used by supporters of the Ayatollah Ruhollah Khomeini.

"We aren't followers of Khomieni and we don't believe in his holding Americans hostage in Iran," said one Afghan marcher. Across the street, two Iranian students carried a green banner identifying themselves as the "Islamic Association of Afghan Students."

But one Afghan at the second march said, "It doesn't matter who carries whose flag."

"Down with Russian imperialism!" chanted the marchers. "Down with U.S. Imperialism! Long live the revolution in Iran."