Leading Article: The start of a long haul

THE MOST important point to remember about the final signature on the Vance-Owen plan for Bosnia is that it was achieved only by convincing Slobodan Milosevic, the Serb leader in Belgrade, that sanctions would be applied in earnest and that the Americans were on the brink of using force. He and his colleagues began to calculate that the cost of attempting further military conquest would be too high.

Mad though the Serbs are in many respects, they have been operating rationally on one level. They understood early on that it was safe to pursue the creation of Greater Serbia for as long as the Western community remained unwilling to respond with force. Two years ago they discovered that they could occupy large chunks of Croatian territory without anybody stopping them. When they started the war in Bosnia they looked at the disarray in the West and remained confident. But, just in case, they played for time by stretching out negotiations and signing dozens of meaningless ceasefires in order to lull the West into believing that a peaceful settlement was imminent, thereby slowing any impetus for intervention.

They may still be playing that game, in which case the fighting will continue, but it looks more probable that Mr Milosevic has opted for a tactical pause in the hope that sanctions will be eased and plans for military intervention put aside. What is certain is that neither he nor other Serbian leaders have abandoned their aims. Serb nationalists see themselves as embattled, misunderstood victims of history who will not be safe, nor able to walk with pride, until they have brought all Serbs together in a single, powerful state. Their dream is retrograde, racialist and wholly out of tune with the need for people of varied ethnic backgrounds to live together - as they have done for centuries in Bosnia - but it is far too strongly held to be signed away by a few transitory politicians under pressure. Its eradication will require years of re-education and cultural change.

Meanwhile it must be contained before it does further harm. Fortunately Western leaders have belatedly learnt to be sceptical of agreements signed by Serbs, so talks on military intervention are continuing and the sanctions will, it is said, be lifted only when deeds follow words. The Serbs, Croats and Muslims are being told that they must co-operate fully in implementing Vance-Owen. This means ending the fighting and withdrawing Serb forces from large areas of conquered territory.

It will be a miracle if this goes smoothly, but the chances will be higher if the threat of outside force remains as credible as it seems finally to have become. More than a year ago there was an agreement to demilitarise the Serb-occupied areas of Croatia and allow refugees to return. The agreement has not been implemented, partly because the UN mandate is too weak. UN forces look on impotently as Serbs flout the agreement and Croats prepare to recapture the territories by force.

The same mistake must not be made in Bosnia. The Serbian leadership can read Western newspapers as well as anyone else and may still be unconvinced that Western leaders have the will to persevere. Almost certainly there will be tests of Western determination. If the response is weak or confused, the Serbs will be tempted to take chances and the agony of Bosnia will be prolonged. Although the Serb signature on the Vance- Owen agreement is encouraging, it means nothing without implementation. Even if that goes relatively well, a long, hard, perilous slog lies ahead.