Nothing better highlighted the contrast between the present failures to bring peace to Kosovo and the success, four years ago, in bringing it to Bosnia, than the visit to Yugoslavia last week by the star US envoy, Mr Richard Holbrooke.

Mr Holbrooke was the architect of Bosnia's Dayton peace agreement, and earned the nickname Balkan Bulldozer for a confrontational style which bullied the protagonists into signing the deal.

Back then, President Slobodan Milosevic of Yugoslavia had to wait in the cold evening air outside Mr Holbrooke's office in a US air base before learning what terms he would get. This time, Mr Milosevic sent the American away with a flea in his ear, refusing demands to sign a Kosovo truce.

Mr Holbrooke's failure has meant another frantic weekend of shuttle diplomacy as international envoys try to get a deal on the table in time for the latest round of talks in Paris today. But the truth is that Kosovo is failing because the West has forgotten the lessons it should have learned from its belated success in Bosnia. The first lesson is an obvious one for mediators all over the world: mean what you say.

In 1995, the West had already been bombing the Bosnian Serbs for several weeks before the first delegate touched down at Ohio's Dayton air base. The Serbs knew the West was united, and would not hesitate to continue bombing if they did not put pen to paper.

Back then, there was unity among what were once called the Great Powers, who wanted Bosnia's war over and would not be played off against one another.

This time, there is non-stop squabbling. The US wants to bomb Mr Milosevic if he refuses to agree not just a peace treaty, but also the peacekeeping troops to enforce it.

But Russia objects, and NATO members are also unsure, with France and Italy unwilling to support air strikes. With US prodding, NATO officials continue to talk tough, but there is uncertainty in their voices. There is also a world of difference between saying the alliance "may" bomb and saying it "will" bomb. Ask Mr Milosevic. He is unlikely to talk seriously about anything unless convinced NATO means business.

Lesson two must be - never bluff in the Balkans.

The third lesson - the secret of success is in the preparatory work.

By the time Dayton kicked off in autumn 1995, there had been months of preparation - years, if you include the experience of so many previous peace efforts. The key to its success was a plan hatched by the Americans. They already knew Yugoslavia, exhausted by war and sanctions, wanted peace, and would make sure the Serbs in Bosnia would sign a deal.

Next, US military advisers helped ensure that Croatia cleared Serbs from a key region, the Krajina, in the summer. With its own war objectives satisfied, Croatia too was happy to end Bosnia's war, and to bully Bosnia's Croats into signing a deal.

That left the Muslims, who were cut off by Croats in the south and Serbs in the north. They were offered enticements such as aid, a new army and control of Sarajevo - but also told they had no choice. They were now cut off and their enemies would sign a deal without them.

Kosovo, by contrast, has seen only muddle. The "peace process" began in earnest only in January, after the massacre of 45 ethnic Albanians in Racak village. But everything has been rushed. The first round of talks in France, at Rambouillet chateau, were delayed when Serbs refused to let guerrilla chiefs fly out of Kosovo.

Then it emerged that neither of the key players - Mr Milosevic for the Serbs, guerrilla hardliners for the Albanians - would be at the talks. After 16 days, and despite boasts from the Anglo-French hosts that the delegates would never leave the castle without an agreement, Rambouillet ended in failure.

A new conference was then announced, with France trying to copy the Dayton model by holding it at a grim air base in Normandy. Then that idea was scrapped in favour of the grandeur of Paris. But still neither side is near signing.

Now the Americans are in a new muddle. They cannot threaten to bomb Yugoslavia if the Albanians have also not signed the deal. Yet the Albanians, conscious that today's Paris deadline is probably as flexible as the Rambouillet ones, are in no hurry.

The deal itself is awkward, because it avoids the only question that really matters - independence. The Albanians, who make up 90 per cent of the population, have long insisted that they should have a right to leave Yugoslavia.

But Kosovo is also sacred Serb territory, containing its most famous battlefield and most important churches, and Yugoslavia insists on hanging on to it. The West agrees, frightened that independence in Kosovo would lead to a flood of copycat independence wars around the globe.

So the proposed agreement is for Kosovo to have autonomy for three years, after which all options - including a new war - remain open. It might have worked - might still work - if the world's large powers all begin singing from the same song sheet. Which brings us to the final, sad, lesson from Dayton.

Many in the West still cling to the idea that today's wars are terrible mistakes. These mistakes can be solved through clever diplomats, such as those deployed by Britain's Foreign and Commonwealth Office and France's Quai d'Orsay, spinning a silken thread of compromise through the competing demands of the warring sides.

This is rubbish because, in most cases, the demands of warring sides overlap. There are no misunderstandings in Kosovo. Both sides understand each other perfectly. But they want very different things. And if there is one thing the Balkan Bulldozer demonstrated all those years ago, and which was proved, by its absence, amid the sculpted finery of Rambouillet, it is that diplomacy counts for little. What matters is one thing: Main Force.