Western governments owe public an explanation on Bosnia: Nato has fired its first shots in anger. Tony Barber, East Europe Editor, assesses the consequences

IT HAS taken 45 years, but it has finally happened. Nato, the strongest military alliance in history, the defender of Western civilisation, the guardian of individual liberty, has fired its first shots in anger. We are in a new world.

The destruction of four Serbian planes over central Bosnia-Herzegovina yesterday does not mean that the West is engaged in a full-scale war. But those explosions in the skies have changed the structure of international relations. Gone is the black-and-white world of East-West confrontation. Gone, too, is the fleeting mirage of a New World Order, a place where responsible powers were supposed to work together for the cause of security. Welcome, instead, to a world of uncertainty and upheaval, of clashing nationalisms and murky wars where the West thinks, but is not quite sure, that it must unleash its weapons for the sake of its own credibility.

When the foreign ministers of 12 Western countries signed the treaty establishing the North Atlantic Treaty Organisation on 4 April 1949, it is a fair bet that none of them expected the alliance to fire its first shots in the middle of the Balkans. Berlin, perhaps, but not a few miles from Banja Luka, a place that lies outside Nato's frontiers.

Now that Nato has struck, the West has no escape route from Bosnia short of utter humiliation. It is therefore a matter of the highest urgency for Western governments to tell their publics what, precisely, is the goal of Nato policy in the Balkans. Since the wars of the Yugoslav succession broke out in June 1991, there have been too many switches of direction, too many disputes inside the Western alliance, too much confusion over how far to involve the Russians and, above all, too little long-term thinking.

This is not a conflict like the Gulf war against Iraq. There, the West had a clearly defined and legitimate objective: to end the Iraqi occupation of Kuwait. If, in the course of that action, Saddam Hussein was prevented from posing a future threat to other countries in the region, including Israel, then that, too, was a reasonable objective.

But in Bosnia, as in the rest of former Yugoslavia and the Balkans as a whole, it has never been clear what the West stands for. Shots have been fired, aircraft have been destroyed, but in the name of what? We have a military policy, but our political strategy lacks coherence.

It is instructive to recall that, only three summers ago, the West was upholding the principle of a united Yugoslavia. Slovenia and Croatia were warned against secession. By the end of 1991, a complete reversal of policy had taken place and the West was promoting Slovenian and Croatian independence.

The consequence was that the West also had to endorse independence for Bosnia-Herzegovina, for otherwise the Muslims and Croats of that republic would be vulnerable minorities in a Serbian-dominated rump Yugoslavia. But the West then did absolutely nothing to protect Bosnia. It admitted the newly independent state into the United Nations at a time when it was clear that President Slobodan Milosevic of Serbia and President Franjo Tudjman of Croatia were colluding in Bosnia's partition.

By mid-1992, the damage was done. The West had adopted the mantle of Bosnia's protector but refused to come to its defence. Making the best of a bad job, Lord Owen and Cyrus Vance, the West's mediators, devised a plan for turning Bosnia into a republic of 10 provinces in which the central government's powers would be kept to a minimum and Muslims, Serbs and Croats would, as far as possible, administer their own affairs.

It was in principle not a bad plan, for at least it preserved the idea of Bosnia's territorial integrity. But it had several flaws. First, it needed a substantial commitment of UN forces to be workable, and Western governments could not summon the will for such an operation. Second, it appeared to reward the Serbs with land, where Muslims were the largest nationality before they were subjected to killings and forced expulsions. It also handed Mostar to the Croats, though the town had a slight Muslim majority before the war. This led to the third flaw: the absence of US support for the plan on the grounds that it was unfair.

The next Western initiative came close to acknowledging that Bosnia had ceased to exist. It was a plan, again bearing Lord Owen's stamp, that called for a three-way division of Bosnia into Serbian, Croatian and Muslim regions. Few seriously expected that the Serbian and Croatian areas would refrain from merging with Serbia and Croatia proper. Even fewer considered how to organise the massive population transfers that would be necessary to implement the plan.

As before, the US - backed by Germany - withheld support from the proposal. Why should the Muslims be pushed into an unjust settlement? It was a fair point, and it buried the plan. But still there was no agreed Western policy.

The Sarajevo marketplace massacre last month caused the buck of Bosnian peace-making to pass to the Americans. Their idea is to construct a Muslim-Croat unit in Bosnia that will then form an alliance, possibly even an administrative connection, with Croatia.

But this initiative begs important questions. Does the West uphold the principle of Bosnia's unity, or is it saying that, once the Muslims and Croats are packaged together, the Bosnian Serbs can merge with Serbia? If the latter, then what about all the towns on the Drina river in eastern Bosnia where the Serbs tore Muslim communities to shreds in 1992? If the Serbs are to retain these towns, and ultimately end up with about half of Bosnia, then what was the point of destroying four Serbian light attack aircraft yesterday?

But if the opposite is true, and the West wants to keep Bosnia together, then how will it impose such a settlement on the Serbs? Is the West proposing to beat the Serbs into submission by force? If so, has the West taken into account the implications of Russian opposition?

If Western countries take the view that they have no fundamental interests in the Balkans worth a confrontation with Russia, then their governments should tell us so explicitly and admit that a Bosnian settlement will involve a degree of injustice. At the moment, we have the worst of both worlds: high- mindedness and irresolution. Couple that with military action undertaken without a clear purpose, and the only certainty is that the world is rapidly becoming less safe.