LONDON — London. -- Yugoslavia should make us fear not the Molotov variety, but the Stalin cocktail. It was Josef Stalin, more than any other Soviet leader, who engineered the mixing of ethnic, religious and social groups into one compressed society. Yugoslavia's Josip Broz Tito, who later broke with Stalin, merely emulated him on this point.
Now we watch Tito's creation undo, as Stalin's legacy in the ex-Soviet Union has led to violence in Georgia, Moldova and Azerbaijan, with the threat of worse to come, even inside Russia itself.
As the Stalin cocktail decomposes, another process is afoot in the Western world with profound implications for disintegrating Western Europe.
Some would call it isolationism. It is not. In today's world, even the moderately educated can see that we are all woven together like a Persian carpet by economics, institutions and television. It shows in the fact that we are never indifferent for long to immense suffering in other parts of the world. ''Compassion fatigue'' was a misnomer if ever there was one. The compassion today for Bosnia and Somalia is as fresh and uncynical as if the word had only just been minted.
No, what is at play is not isolationism but a growing consciousness that problems of strife and mayhem cannot always be sorted out by the application of force. The days of the cavalry riding over the hill died somewhere between Vietnam and Afghanistan.
It would be too much to say there is a revulsion against the use of force. But an important body of opinion, not least inside military establishments themselves, has come to question the utility of force in all but the most clear-cut and threatening of situations.
Nothing illustrates this more clearly than the equivocation that preceded the decision to go to war after Iraq invaded Kuwait. If the invasion had happened a generation ago, we could not have imagined the chief of the American armed forces confiding his private doubts about the use of force, or his immediate predecessor in the job publicly telling Congress that it would be more sensible to rely on economic sanctions, or the U.S. Senate approving military action by only the slimmest of margins.
Hence the subtle maneuvering of Western leaders in the face of outraged public opinion demanding they ''do something'' about the killings in Bosnia. All through this Yugoslav crisis the British Foreign Office has constantly advised its European partners that the painful British experience in Northern Ireland has taught it the difficulties of taking on a guerrilla army and the impossibility of fighting ''village by village, valley by valley.''
Now that aroused American public opinion has pushed the U.S. to get involved, there is a second, very firm, hand on the brake -- Gen. Colin Powell.
He has made it clear to his political bosses that any intervention to quell the Serbs would have to be on an absolutely massive scale, that the dangers of getting bogged down for years are very real and that even if only the supposedly ''surgical'' air power were used the Serbs could take hostage U.N. peacekeepers, the Red Cross, U.N. and private relief workers and even whole Muslim villages. Exactly what would be gained in the end if so much was lost in the process?
Such arguments make those who see a great principle at stake in Yugoslavia rather angry. Do we stand by and watch internationally recognized borders be forcibly changed? Do we accept that ''ethnic cleansers'' can be allowed to do their worst? In an ideal world we shouldn't. But what exactly can be usefully done about it?
What the European Community and United Nations negotiators and peacekeepers have done, ineffective as it may be, is an exercise in the art of the possible. One can argue that some of the moves were made too late, but they have made a difference. U.N. peacekeepers are successfully maintaining a peace in Croatia.
And if the blue helmets were sent too late to Croatia and Sarajevo, that is an argument for sending them immediately to Albanian-populated Kosovo, where they might stand a chance of forestalling the likely third phase in the Serbian lunge for control.
What should give the military interveners pause, finally, is the Stalin cocktail. Other Yugoslavias lie in wait all over Eastern Europe. The outside world cannot fight in every one. But the wicked -- when its crystal clear who is wicked -- can be embargoed. Arms supplies can be cut off. Human-rights culprits could be threatened with trial at a newly constituted international court of war crimes.
But evil cannot always be simply ''rolled back.'' The United Nations cannot be asked for its blessing on half a million American troops every time the U.S. president decides the cause is right. The most we can do about this sort of violence is to contain it and isolate its more contagious elements -- and, very important, work to help those who suffer from it with all the charity we can muster.
Jonathan Power writes a column on the Third World.