European Union efforts to mend relations between Kosovo’s Serbian and Albanian communities are unraveling as violence spills across the north of the country.

The worst clashes in a decade erupted on Monday when NATO-led peacekeepers were called in to contain clashes between Serbian protesters and the Kosovo police. Thirty soldiers and dozens of Serbs were injured.

With the backing of the US, the EU has been leading talks between the Kosovo government and neighboring Serbia in a bid to resolve disputes that are blocking their path to eventual EU membership. While the most substantive issue is Serbia’s refusal to recognize the independence of Kosovo, which formalized its break from Belgrade in 2008, the enmity between the two communities dates back to the war in Kosovo a generation ago.

Russia and China have both backed Serbia’s position, adding a geopolitical dimension to the dispute, and helping to perpetuate the divisions which haunt the countries of the former Yugoslavia.

The standoff has condemned the northern part of Kosovo, mainly populated by Serbs, to economic limbo, paralyzed by the frosty relations between Pristina and Belgrade while the ethnic-Albanian majority in the rest of the country has enjoyed relative prosperity.

The flareup comes at a critical moment for the western allies who have backed the Kosovo state since its creation. Ukraine’s fight against the Russian invasion is delicately poised and the US and the EU are trying to push back against the Kremlin attempts to win support in countries like China, India and Brazil and to portray NATO as the aggressor.

That means that western diplomats have limited bandwidth to focus on another flare up on the European continent, even as they worry that getting drawn into another crisis could offer fuel to the Kremlin’s propaganda operation.

The immediate trigger for the protests was the municipal election held in April which local Serbs boycotted, with the encouragement of Serbia President Aleksandar Vucic. Kosovo Prime Minister Albin Kurti pressed ahead with the vote, despite warnings from the US and the EU that it would exacerbate tensions.

With ethnic Albanians winning office in Serb-dominated towns, those tensions spiraled out of control last week when the newly elected mayors started to arrive at their offices.

On Tuesday morning, mayors were jeered by hundreds of local Serb protesters as they were escorted to their offices by Kosovan police. The Kosovo government rejected Serb demands to withdraw the officials from their posts.

“There was no good option for the Kosovo government here, but trying to install their elected local officials is a better option than giving up on the North,” said Aidan Hehir, international relations professor at University of Westminster.

Schools have been closed from Monday as parents feared for safety of their children, given the heavy military presence in the area populated by about 50,000 Serbs.

Vucic on Friday put his army on high alert and moved some units nearer to the border, fueling concerns in Serbia about just how far the situation in northern Kosovo could deteriorate. Belgrade was forced by NATO to withdraw its forces from Kosovo in 1999.

For Kurti, the move is part of his determination to show that his government can govern all of Kosovo’s territory, not just the areas dominated by ethnic Albanians. The Serbs say he’s reneged on a deal to give them more autonomy.

Emboldened after he won 50% of votes in the last general election, Kurti has pushed through his vision of Kosovo despite the criticism from the West.

Vucic, for his part, is also facing recurring protests at home despite winning nearly 60% of the vote in last year’s election. He’s already raised the possibility of holding a snap vote to consolidate more power and shake off the threat from any opposition voices, although compared with Kurti, he’s faced relatively little public criticism from the EU and, in particular, the US.

“The US position has shifted significantly to this naïve notion that if they are nice to Vucic, he will become part of the West,” Hehir said. “The irony is that, while Vucic’s situation becomes shakier in Belgrade, the West seems to be propping him up.”

--With assistance from Andrea Dudik and Zoe Schneeweiss.