“EVERY idiot with a map and rifle is getting excited,” says an international official in Pristina, the capital of Kosovo, still barred from membership of the United Nations ten years after it unilaterally declared independence from Serbia. Serbs and Albanians have been transfixed as their leaders have recently discussed swapping pieces of territory populated by tens of thousands of people. It is an idea that is raising hopes and fears across the Balkans and provoking political turmoil in Kosovo itself.

When Yugoslavia, the Soviet Union and Czechoslovakia collapsed in the 1990s their successor states all emerged within existing boundaries. But if Kosovo and Serbia redraw their borders on ethnic lines, that would be a big and possibly destabilising change for the region. It would mean, for example, that Bosnia’s Serb leader could ramp up his own demands for independence by arguing that Yugoslavia’s old internal borders had now been breached and so Bosnia’s could now be too. That would risk a new war.

Almost unnoticed, a first ethnic boundary change is about to take place. On September 12th the municipality of Gracanica, a Serbian-majority area in Kosovo, voted to hand over part of its territory to a neighbouring Albanian-majority district. A new ethnic-Albanian housing estate has changed the proportions of Serbs and Albanians in Gracanica, so this is a way for the Serbs to get rid of Albanians. Changing the borders of the two states would not be so easy. It is also highly controversial. It would, argued an op-ed in the New York Times, be both “a peaceful form of ethnic cleansing” and “the right thing to do”.

More than 90% of Kosovo’s population are ethnic Albanians and perhaps 5% are Serbs. Serbia does not recognise Kosovo and, excluded from the UN, its statehood is also rejected by several countries, including Spain and Russia. The essence of the deal is that the Serbian-inhabited north of Kosovo, which the government in Pristina does not control, should be returned to Serbian sovereignty. In exchange Serbia would give Kosovo the Presevo Valley in south Serbia, which is predominantly ethnic Albanian, and recognise Kosovo. Part of any deal would have to involve Russia and China dropping their veto on UN membership for Kosovo.

In August, when Albanians of the diaspora were home for the holidays, the Presevo Valley was buzzing. Parents snapped in Swiss German and Belgian French at their children. Local Albanians are thrilled at the thought of living in one state with fellow Albanians in Kosovo. Local Serbs believe it will never happen. After all, said Marko, aged 22, who runs a grocery shop, Serbs and Albanians have never resolved disputes peacefully, so why would they start now? Nearby, bulldozers were finishing the motorway which runs through the valley, alongside the railway. These transport routes link Serbia to central Europe and Greece. It is hard to believe that Serbia will give them up.

Over in Kosovo, the mainly Serbian village of Babin Most sits on a hill overlooking the battlefield where the Serbs famously lost the battle of Kosovo to the Turks in 1389. It is not in the north, the area which would become part of Serbia again. The majority of Kosovo’s 120,000 Serbs do not live in the north and so they are horrified by the thought that Serbia might, as they see it, give up on them. Father Sava, the abbot of Kosovo’s Serbian medieval monastery of Visoki Decani, has been campaigning loudly against division. For this he has earned the enmity of Serbia’s government-controlled press, which has declared him a traitor.

In Pasjane, another Kosovo Serb village, there is a street named for Dobrica Cosic, an influential novelist who died in 2014. He regarded Kosovo and its Albanians as a “cancer”, to be surgically removed by partition.

Both the EU and America had previously rejected the redrawing of borders on ethnic grounds, believing it would destabilise the region. They have now given a green light to Kosovo’s president, Hashim Thaci, and Aleksandar Vucic, his Serbian counterpart, to see if they can strike an agreement. Yet it will be difficult, if not impossible. On September 7th Mr Vucic refused to meet Mr Thaci in an EU-sponsored meeting in Brussels. Then he went to Kosovo and praised Slobodan Milosevic, Serbia’s wartime leader, who repressed ethnic Albanians and then ethnically cleansed hundreds of thousands of them during the Kosovo war.

Mr Vucic wants a guarantee that if there is a deal, Serbian membership of the EU will follow. That is an undertaking the EU cannot give. But it is clear that even raising the issue has opened new perspectives for the region. “There are always other options,” says a senior Kosovo Albanian leader. He means that unless Kosovo is recognised by Serbia and can join the UN, it can unite with Albania instead. Some nationalist Serbs who understand that Kosovo is lost to them might welcome that. If there was a Greater Albania then they could demand a Greater Serbia by claiming the Serb part of Bosnia, which was what Mr Milosevic fought a war for.