The party is over. Serbia's response to Kosovo's declaration of independence last Sunday has been as uncompromising as pessimists feared. Checkpoints on the border between the two nations were destroyed by enraged Serbian protesters earlier this week. Nato reinforcements had to be dispatched to prevent the protesters from storming into the new state. There has been sporadic violence in the Serb-dominated districts of the divided Kosovan city of Mitrovica too. But the Serbian capital Belgrade has witnessed the most disturbing scenes. On Thursday, following a rally in protest at Kosovo's secession, a mob set fire to the US embassy and also attacked the British, Croatian, Belgian and Turkish consulates.
The strict limitations on Kosovan independence and guarantees for the rights of the Serb population within the country appear to have done little to appease the anger of the Belgrade government. Serbia has ruled out military action in response to the declaration of independence, but its leaders are clearly determined to do nothing to calm domestic passions over the breakaway of what many Serbs regard as their cultural heartland.
Serbia's minister for Kosovo declared the assault on the border posts "in accordance with general government policies". In his view, the destruction was "not nice but legitimate". Meanwhile, at Thursday's rally the Serbian Prime Minister Vojislav Kostunica declared "as long as we live, Kosovo is Serbia". These are words designed to whip up anger, not assuage it.
It is true that yesterday Mr Kostunica condemned the "brutal violence" at the US embassy, but other politicians were slow to do so. And it has been noted that there appeared to be no police protecting the embassy district, despite the fact that it was an obvious target. It has been remarked upon too that riot police made only a belated intervention.
The Kosovan Prime Minister, Hashim Thaci, has compared the mood in Belgrade to that of a decade ago, when Slobodan Milosevic ordered the persecution of ethnic Albanian separatists in Kosovo. While such scenes are not about to be repeated, the violent partition of the Serbian majority districts of Kosovo from the ethnic Albanian areas is a real possibility unless the Serbian government gets a grip.
Can such a disastrous outcome be avoided? That largely depends on whether the carrot of European Union membership proves more alluring to the Serbs than the desire to scupper Kosovan independence. In some respects this avenue to stability is unpromising. A preliminary membership deal with the EU was reached last year, but collapsed because of Serbia's continued failure to co-operate fully with the United Nations war crimes tribunal for offences committed during the break-up of the former Yugoslavia. The EU was ready to sign an interim trade agreement with Belgrade earlier this month, but Mr Kostunica blocked the move over European plans to support the fledgling Kosovan state with a 2,000-strong policing mission. Since the declaration of independence, diplomatic relations have deteriorated even further, with Serbia withdrawing its ambassador to Britain and other European nations that have recognised Kosovo.
But there is hope. The Serbian Foreign minister, Vuk Jeremic, was careful to make it clear this week that Belgrade's argument is with individual EU countries, not the EU as a whole. And the Serbs rejected the hard-line presidential candidate, Tomislav Nikolic, earlier this month in favour of the pro-EU Boris Tadic. A deal can still be done between Serbia and the EU. Indeed, if Kosovo's birth is not to be drenched in violence, it will have to be.