RUSSIAN PRESIDENT Boris Yeltsin's use of soldiers, tanks and planes to try to subdue the breakaway republic of Chechnya has plunged him into a lose-lose situation.

If the unpopular war goes badly, the unpopular Yeltsin could see his presidency end, either in the 1996 election or sooner through a coup d'etat.If the war goes well and seems to succeed, the Russian Army will get the credit, not Yeltsin. Then its leaders will have rescued Yeltsin twice - once by shelling Parliament and again in Chechnya - and may well decide they no longer need him.

In either case, a long guerrilla war is likely to follow. The rugged terrain of the northern Caucasus, populated by Russia-hating Muslim peoples, could turn out to be Moscow's "second Afghanistan."

Though they number only 1.2 million, the fiercely independent Chechens will hardly be easy foes. It took the czars 50 years to subdue them in the 19th century. They never have willingly accepted Russian rule.

A measure of the Chechens' military prowess: A czarist general, fighting another Caucasian tribe in the last century, was asked what he needed to win. "One Chechen," he replied.

Interestingly, opposition to Yeltsin's war comes not only from the president's former democratic and reformist allies, whom he has abandoned. Top military men also criticized his resort to force to quash Chechnya's self-proclaimed independence.

In a sign of disarray in the Russian Army, two deputy defense ministers, Gens. Boris Gromov and Georgi Kondratyev, publicly denounced the move. Gromov, an expert on guerrilla warfare and the last Soviet soldier to leave Afghanistan, said he would not send his conscript son to Chechnya.

In addition, one of Russia's most pugnacious and insubordinate generals, Alexander Lebed, said Yeltsin had blundered. Lebed is an admirer of Chile's former dictator, Gen. Augusto Pinochet, and fancies himself as Russia's Pinochet.

He may get his chance. In a poll, 70 percent of the servicemen in and around Moscow preferred Lebed to Defense Minister Pavel Grachev, who is suspected of corruption. Those servicemen would be the key to any coup.

With so much at risk, why did Yeltsin finally send troops into Chechnya three years after the republic's president, former Soviet Air Force Gen. Dzhokhar Dudayev, declared independence?

Yeltsin may not have had a choice. Chechnya is rich in oil and minerals, and pipelines from the Caspian Sea to the Black Sea cross its territory. More important, if its sovereignty bid is accepted, some 20 other ethnic republics could try to secede from the Russian Federation.