America and other Western nations issued a sharp rebuke to the Serbian Government yesterday, after the worst riots in Belgrade since the fall of Milosevic led to the burning of the US Embassy and attacks on those belonging to Britain, Germany, Croatia and Turkey. The European Union promptly froze all further discussion of a new partnership with Serbia until the situation had calmed down, and US missions across the Balkans were put on high alert. The riots, prompted by anger at the West's recognition of Kosovo's independence, were blamed by the Serbian authorities on “hooligan elements”, but were clearly incited by nationalist politicians. Vojislav Kostunica, the Prime Minister, had earlier called a rally against independence a “magnificent” demonstration of Serb feeling.

Russia, which has fiercely opposed the independence declaration, blamed the West for not anticipating the reaction. Its envoy to Nato said in frustration that Moscow might have to turn to “brute military force” to make itself heard if Nato overstepped its authority in Kosovo. Much of this is probably bluff. Western governments anticipated trouble, must remain on alert in the Balkans and will need to hold their nerve in the coming weeks. What matters is that the Serbian Army remains in barracks, and that Russia has made it clear it would not become involved in any armed conflict over the breakaway province.

The flashpoint is in Kosovo itself. Thousands of Kosovan Serbs, swelled by kinsmen from across the border, clashed with United Nations police yesterday in Mitrovica, the main town in the three northern Kosovo provinces where most of the 100,000 ethnic Serbs live. They are hoping to thwart any attempts by the Albanian majority Government in Pristina to exercise authority over them, swearing continued allegiance still to Belgrade. Their case may indeed find support not only in Russia: those European Union countries worried by the Kosovan precedent may argue that if the province's independence is accepted as a special case, the logic of the Serb provinces joining Serbia should also be accepted.

Such arguments may challenge international lawyers; in practice, they are wholly impractical. To reopen the debate about the status of Kosovo risks unravelling the decision reached after months of consultation by the EU special negotiator. Nato's 16,000 peacekeepers cannot be asked to police Pristina's inevitable attempts to stop the Serb provinces' secession. Of course, it would have been better had Kosovo's status been decided immediately after the defeat of the Serb forces in 1999. The link between Milosevic's repression and Albanian rejection of rule by Belgrade would have been clearer; and the consequences of their disastrous nationalist adventurism would have been easier for the chastened Serbs to accept. But that moment has passed.

Now the West must understand Serb petulance and attempt to forestall a further descent into nationalist isolationism. EU engagement of Serbia will bring the political and economic changes that, especially for a frustrated younger generation, can make the loss of the historic sites less painful. Within an EU framework, national boundaries become less important and less divisive. As anger subsides, Serbs and Kosovans may resume some links. With outside support and patience, they may even become good neighbours.