Two days of high-level talks in Macedonia between Nato and Yugoslav officers on the pull-out of the Serb-dominated Yugoslav security forces from Kosovo broke down in the early hours of Monday morning.

But why is Belgrade refusing to sign up to the troop withdrawal deal?

Talks between Nato and Yugoslav officials got underway within 48 hours of last week's deal to produce a speedy timetable for the evacuation of the Yugoslav army and Serb police from Kosovo.

But by Monday the high-level talks had broken down, as the commander of the planned Kosovo peacekeeping force, the British general, Sir Michael Jackson explained.

"The Yugoslav delegation presented a proposal that would not guarantee the safe return of all the refugees or the full withdrawal of Yugoslav forces.

"Nato therefore has no alternative but to continue and indeed intensify the air campaign until such time as the Yugoslav side are prepared to agree to implement the agreement fully and without ambiguity," he said.

Complete withdrawal

According to British officials, the weekend talks had failed because the Yugoslav delegation had gone back on several key issues of last week's accord.

The deal Belgrade accepted calls for an initial complete withdrawal of Yugoslav security forces from Kosovo; but at the talks this was questioned by the Yugoslav side which proposed scaling down its forces to peacetime levels - perhaps 15,000 troops.

General Sir Michael Jackson said Nato had no alternative but to step up bombing

Yugoslav officers also said they could not pull out within the one-week deadline specified in the deal.

Apart from these military aspects, Belgrade also appears to be insisting that before the withdrawal details are agreed, a UN Security Council resolution needs to be passed on the deployment of an international peacekeeping force.

This insistence could, indeed, be the key to Belgrade's reasons for adopting once again an apparently non-cooperative approach.

The reference to the peacekeeping force in the outline agreement was kept deliberately vague to paper over the wide cracks between Russia and the West.

Nato is adamant that the unified command should, in practice, be in its hands; Moscow does not want Russian troops to serve under Nato's command.

But this dispute would lose much of its practical relevance if Belgrade had now agreed to the withdrawal timetable. Within a matter of days Yugoslav troops would be well on their way out, Nato's bombing would be suspended and Nato troops, already deployed in neighbouring Macedonia, would be ready to move into Kosovo straight away.

Confrontation

If after that sequence of events Nato and Russia would still not have agreed a deal on the peacekeepers' command structure, Moscow might have blocked a UN resolution or refused to deploy its forces, but from Nato's point of view - with its troops already deployed in Kosovo - it would have mattered little.

Bombing would be suspended within days if Serbs agreed to the deal

If on the other hand, all that sequence has to follow a prior UN vote, the whole peacekeeping operation can be scuppered for the time being, and the row between Russia and Nato would once again come out very much into the open.

President Milosevic may view a renewed confrontation between Moscow and the West as his last chance to salvage something from his defeat over Kosovo.

In the meantime, Belgrade is still hoping to reduce the presence of Nato countries in the planned Kosovo peacekeeping force.

Vladislav Jovanovic, the Yugoslav envoy at the UN, said: "Those countries who were most exposed in the aggression on Yugoslavia are not preferred to be part of the team, saying this, I don't say that they are going to preclude it, it is a matter of debate."

It is unlikely President Milosevic's last-ditch attempt to stir up further trouble between Russia and the West will do more than delay the painful moment when he has to pull his forces out of Kosovo.

Serbian 'sell-out'

But for now, he is also gaining time and this could be useful for several reasons.

On a practical level, it will provide further opportunities to destroy evidence of alleged atrocities against Kosovar Albanians or perhaps to increase physical destruction to make the eventual return of Kosovar Albanian refugees more difficult.

Besides, Mr Milosevic is also facing trouble at home for agreeing a deal that was in most respects worse than what he had turned down before the bombing at the Rambouillet talks.

His opponents - and not just the ultra-nationalists among them - are saying that he has sold out Serbian interests in Kosovo.

Mr Milosevic can now point to Nato's renewed bombing to demonstrate what refusal to do a deal with Nato actually means; and and claim that his opponents have no credible alternative.