Talks between Serbia and Kosovo on a possible redrawing of borders largely along ethnic lines are threatening to reignite a familiar European tinderbox.
Despite questions over whether they even have a mandate to do so, Serbian President Aleksandar Vucic and his Kosovo counterpart Hashim Thaci have embarked on high-level talks that could envision Kosovo's Serb-dominated north coming under Belgrade's rule in exchange for the Albanian-dominated Presevo Valley in south Serbia being handed to Pristina.
The idea is incendiary enough that Thaci has avoided calling it a redrawing of borders, but instead uses the phrase "correction" to describe any possible changes.
But no matter what the wording, Western diplomats, Balkan analysts, and even those on the ground say any moving of the borders could destabilize a region that has struggled to come to terms with the violent breakup of the former Yugoslavia.
Perhaps even worse, it is feeding tensions between Serbia's traditional ally Russia, which has been trying to gain influence in the region, and NATO and the European Union, which want to bring the countries into Western structures.
"We have to stop this game by the two leaders, who, if they succeed in their intentions, will cause not only the relocation of families and human victims in Kosovo and Serbia, but will destabilize the entire Balkans," Ilir Deda, an opposition deputy in Kosovo's parliament, told RFE/RL.
"Because the border between Kosovo and Serbia cannot be changed without affecting Macedonia, Montenegro, and Bosnia-Herzegovina. Not to talk about Eastern Europe," he added.
Kosovo didn't exist as a country until it broke free from Serbia in 2008, nearly a decade after a NATO-led bombing campaign pushed out Serbian forces to end a brutal crackdown on ethnic Albanians during a two-year battle for independence.
Europe's youngest country's 1.8 million population is more than 90 percent ethnic Albanians and about 5 percent ethnic Serbs.
Western powers always hoped Kosovo would mature into a stable, multiethnic state. To that end, there are some 5,000 NATO troops still stationed in Kosovo, which is recognized by more than 110 countries but not Serbia, Russia, China, or five of the European Union's 28 members.
Changing the border could open Pandora's box across the entire Balkans, and not just Serbia and Kosovo, according to Carl Bildt, the former Swedish prime minister who served as the European Union special envoy to former Yugoslavia from June 1995, co-chairman of the Dayton Peace Conference in November 1995, and high representative for Bosnia-Herzegovina from December 1995 to June 1997 immediately after the Bosnian War.
He worries the move could lead to a reopening of the debate over the future of Bosnia and that "there is the even more difficult and dangerous issue of Macedonia, where Albanians are a substantial part of the population."
If the Albanian areas of the wider region start coming together also through a process of territorial swaps, there will certainly be those asking why this should not apply to Macedonia as well, he said.
"Playing with borders and divisions in the Balkans was dangerous in the early 1990s, and remains so now," Bildt wrote in an opinion piece for The Washington Post on August 9. "Further Balkanizing the Balkans is a recipe for disaster."
So why would Vucic and Thaci risk so much?
Both countries are looking to join the European Union, and for that to happen they must normalize relations.
Serbia considers Kosovo the cradle of its history and religion, and the preamble to the Serbian Constitution describes Kosovo as an "integral part" of its territory. As many as 120,000 ethnic Serbs live in Kosovo, compared with about 70,000 ethnic Albanians who live in Serbia.
Amid mounting speculation, Vucic acknowledged on August 9 that he was prepared to compromise on defining Serbia's borders with Kosovo.
Five days later, Thaci told Reuters that he would present his plan "to correct the border" to Vucic when they meet in September in Brussels as part of a dialogue sponsored by the EU that began in 2011 as the two sides tried to iron out issues including control over Kosovo's energy infrastructure, the freedom of movement of citizens, and the future of ethnic Serbs who remain inside Kosovo.
The arduous process of building stability in the Balkans was recently given a boost by an agreement between Macedonia, which also has a sizable Albanian minority, and Greece over what to call Macedonia, which is officially known in the UN as the former Yugoslav Republic of Macedonia (FYROM).
While Washington and Brussels have been pushing for an agreement, the statements from Pristina and Belgrade still shocked many European diplomats and politicians.
German Chancellor Angela Merkel said on August 13 that the border is "inviolable," but concern is less apparent in the United States, which recently seems to be taking the position that it will accept whatever is agreed by the two sides. That is widely regarded as a significant policy shift from previous U.S. administrations, which were openly against the redrawing of Kosovo's borders.
"The current U.S. administration is ready to at least take into account on an equal footing our proposals for the resolution of major problems in the region -- a lasting solution to the Kosovo and Metohija problem certainly being one of those," Serbian Deputy Prime Minister Ivica Dacic said in a statement after a recent visit to Washington.
"This is a huge change compared to only two years ago, since in all talks with the representatives of U.S. institutions it was maintained that the Kosovo issue had already been resolved.... Today, a compromise solution is openly supported," he added.
Lurking in the not-too-distant background, however, is Russia, which is likely to treat any partitioning in the Balkans as a validation of its claims in Ukraine (Crimea), Moldova (Transdniester), and the breakaway Georgian regions of Abkhazia and South Ossetia.
All of the speculation has even worried Serbia's Orthodox Church.
"Partition of Kosovo would lead to one of the most serious destabilizations of the security situation in the last 20 years in Europe. It would cause a huge human tragedy & leave deep wounds. Anyone who knows the Balkans well can't find any common sense in this preposterous idea," Father Sava Janjic, abbot of the Serbian Orthodox Visoki Decani Monastery in Kosovo, tweeted.
"After years of forceful ethnic cleansing in the Balkans & reshaping of ex-Yugoslavia into ethnic clean entities there is a new danger of an agreed land-swap which would be nothing but a consensual exchange of populations -- an agreed completion of ethnic cleansing in Kosovo," he added.