Mikhail Gorbachev offers the West a choice of plague or cholera. By claiming that he did not know that Soviet troops would use deadly force against civilians in Lithuania, Nobelist Gorbachev pleads not guilty by reason of incompetence or impotence in controlling the Soviet military in a predictably explosive situation.

What did Gorbachev know and when did he know it? That question is not likely to ever be conclusively answered. The Soviet president's weak, unpersuasive explanation of his role is intended to turn aside serious inquiry. It is a geopolitical cop-out.

The violence in Vilnius forces the Bush administration and its partners in Europe to face up to the growing militarization of Gorbachev's policies at home and abroad. Gorbachev is a reformer overtaken by the hard-line reaction that his own vision and courage have triggered. He accedes, willingly or not, to the resurgence of an old guard that he failed to dismantle completely.

The Soviet-U.S. summit in Moscow scheduled to begin Feb. 11 is now threatened not only by the shadow of hostilities in the Persian Gulf but also by the continuation of violence in the Baltic Republics. Soviet-American relations, the one seeming bright spot in this winter's gloom, are also now under a cloud.

Gorbachev's explanation implicitly asks Western governments to continue to consider him to be the good czar who would act differently if only he were aware of what his agents were up to. Initial reactions indicate the West will accept this pretense. But the corollary of Gorbachev's statement is that he cannot avoid responsibility for any new violence.

U.S. policy makers have been concerned about the growing assertiveness of the Soviet military in the Kremlin since last autumn. Gorbachev's signature of the Conventional Forces in Europe (CFE) treaty in Paris in November was immediately followed by three mystifying Soviet violations of the accord.

The treaty infractions were not in themselves threatening, given the continuing unilateral Soviet withdrawals of manpower and armor from Eastern Europe. But they raised the same question that the shooting in Lithuania raises about Gorbachev and the military: Who is in charge?

The Soviets have now acknowledged that they shifted 16,400 new tanks east of the Urals to avoid their being destroyed under the treaty's provisions. They also significantly undercounted the equipment left behind in the European theater when the treaty came into effect. The Soviets also unilaterally excluded three naval infantry divisions from the accord's provisions, creating an important loophole for the future.

Still eager to sign whatever can be signed with Gorbachev while he and the Soviet Union are still there, the Bush administration decided not to make a public fuss about these infractions and to continue negotiating for a strategic arms reduction treaty for the Moscow summit. Members of Congress who were briefed on the problems were asked not to go public while Secretary of State Jim Baker tried to use quiet diplomacy to get the Soviets back on a cooperative track.

Baker got nowhere when he pushed Foreign Minister Eduard Shevardnadze on the violations in their meeting in Houston last month. "Shevardnadze simply did not respond," says one key U.S. official. "He had his own problems." Two weeks later Shevardnadze resigned.

His departure was seen in Moscow as a victory for the military, which had openly challenged Shevardnadze over the unification of Germany and over his support for U.S. policy in the Persian Gulf. Seemingly discredited and without a plan of action six months ago, orthodox Communists today offer a program built around respect for the military, law and order and an end to the breakaway movements in the Baltic Republics and other Soviet states.

President Bush has sought to keep the cooperative, friendly relationship he thought he had with Gorbachev intact. When the first news reports of the movement of Soviet paratroopers into the Baltics came last week, Bush ordered key aides to avoid public criticism of the reported move. His action suggested that he has kept faith in Gorbachev longer than did Shevardnadze.

But such restraint is undermined by Gorbachev's cop-out on Vilnius. The administration should not engage in policy-making by mind reading, by guessing at what Gorbachev really thinks about the army's actions. The facts now speak for themselves, and they portray Gorbachev as a man with whom it is increasingly difficult to do business.

The Gulf crisis does not alter this bitter reality. President Bush cannot build a new world order on cynicism, nor on the blood of peaceful Lithuanian citizens. Moscow was never prepared to offer more than political cover for the American effort in the Gulf. If Gorbachev has become a hostage to his military, that cover will be worthless in any event.