How far will President Clinton bend his knee to the murderous thugs who lead Serbian aggression in Bosnia? How far can they push him without a response that preserves American honor? Those questions must be asked after Clinton's disastrous first move in Bosnia. Consider what the president did to defer to Serbian sensibilities--and what he got in return.

Instead of more vigorous action to stop Serbian aggression, as he promised during his presidential campaign, Clinton settled for a humanitarian airdrop to besieged civilians in eastern Bosnia. To avoid offending the aggressors, he said relief supplies would go to all parties--to the attacking Serbs as well as their victims. The Serbian aggressors replied to that deferential policy by using the airdrops as a cover for a major offensive against the Cerska enclave. They overran it, killing hundreds of civilians in what one United Nations official called a "massacre."

Clinton's stand on Bosnia confirms that he is prepared to engage American prestige and diplomacy, but will be cautious about engaging American military power. This approach offers him the comforts of operating within international and national consensus. Yet it may offer Bosnia the agonies of final dismemberment.

Clinton and Secretary of State Warren Christopher might have cynically written Yugoslavia off as a special cultural case that matters little, or have accepted completely the flawed UN plan. It testifies to their conscience and judgment that they decided to cash in some new chips in an effort to improve America's bargaining position in Bosnia.

But the Clinton team takes a painfully constricted position to the table. Without a threat of Western force, Serbia and Croatia will not accept a fair settlement. Yet the military options Clinton now flashes seem an unlikely check on further Serbian defiance. Christopher's pledge to remain "in the back-ground" while the parties reach their own agreement invites the aggressors to hold on to their claims.

The UN and European negotiators, Cyrus Vance and David Owen, made room for American input in their design. Yet, that design, endorsing much of Serbia's and Croatia's ethnic cleansing, remains--and remains defective. Unfortunately the Clinton administration has not put a lot of thought into what changes it would like.

In addition, advocates of the UN plan are reluctant to accept a plan that does not reward Serbian-Croatian aggression and dominance. The prospect of more killing is a powerful consideration in a country that knows of war and terror. But outsiders, who are doing much less than they can to reverse Serbian and Croatian aggression, are poorly placed to tell the Muslim victims that they should learn to live with their misfortune.

Despite his inaction, Clinton seems to understand the stakes of this conflict. In a world riven on ethnic lines, what is to be the international standard for ensuring fair treatment of minorities? The harsh cloud that hovers over the new policy, however, is that at this late date the US may be unable to put together the demanding stance needed to serve those very large stakes. The ends and means of Clinton's policy are at odds.

Bosnia is more than a foreign policy problem. Despite sympathy for the Bosnians, Americans do not support intervention strong enough to make a real difference. To sustain intervention for the years it will take to stabilize the situation would require Clinton to spend scarce political capital that he prefers to save for domestic economic renewal. Clinton may have adopted the airdrop plan as a minimal gesture, hoping to avoid more serious responsibility. Yet he will have to be serious, sooner or later, if he hopes to stop Serbian aggression--and address this widening danger to European security.

There can still be a just peace in the Balkans--not peace at any price--if Europe and the US agree to enforce such a peace together. Serbian President Milosevic must be squeezed until he squeezes the Bosnian Serbs into a bigger withdrawal. That means tightening sanctions on Serbia with a blockade at the mouth of Danube.

The Serbs should at least be required to put their artillery under international control. These guns are their main military advantage; without them the Serbs are likelier to make the necessary concessions. All too much trouble? Consider the alternative.

If the West fails to bring peace to Bosnia, Serbian power will roll over the Muslims, parts of Croatia and the last hope of Albanian freedom in Kosovo. That's just the moral side of the problem.. The practical side is even scarier. If Bosnian turmoil continues, angry Muslim countries might send arms and probably soldiers to their fellow Muslims, where-upon resentful Russians will doubtless do the same for their fellow Slavs, the Serbs.

Our children will not only charge us with appeasement; they will also assert we abandoned part of Europe--and part of the world's future--to avoidable tragedy.