NATO peacekeepers formed security cordons around three Kosovo town halls on Monday to contain groups of Serbs protesting the inauguration of ethnic Albanian mayors in a Serb-majority area following elections that boycotted.
In Zvecan, one of the towns, the Kosovo state police - staffed entirely by ethnic Albanians after all Serbs left the force last year - pepper sprayed a crowd of Serbs, who broke a security barricade and tried to force their way into the municipal building, according to witnesses.
In Leposavic, near the Serbian border, US peacekeepers, equipped with riot gear, placed barbed wire around the City Hall to protect it from hundreds of angry Serbs gathering nearby.
NATO peacekeeping forces also blocked off the Zubin Potok town hall to protect it from the wrath of local Serbs, according to witnesses.
The Serbs, who are the majority in northern Kosovo, have never accepted their declaration of independence from Serbia in 2008 and still consider Belgrade their capital, more than two decades after the uprising of Kosovo Albanians against the repressive Serb government.
Albanians make up more than 90% of the population of Kosovo as a whole, but northern Serbs have long demanded the implementation of the agreement reached in 2013 mediated by the European Union, which provides for the creation of a association of autonomous municipalities in your area.
The Serbs refused to participate in the local elections in April, in which ethnic Albanian candidates won the mayoralty of four Serb-majority municipalities - including Mitrovica North, where there were no incidents on Monday - with a participation of 3.5 %.
The Serbs are demanding that the Kosovo government remove ethnic Albanian mayors from city councils and allow Belgrade-funded local governments to resume their functions. On Friday, three of the four mayors were escorted to their offices by police, who were attacked with stones and responded with tear gas and water cannons to disperse the protesters.
On Sunday, NATO Secretary General Jens Stoltenberg called on the Kosovo government to tone down tensions with Serbia. "Pristina must de-escalate and not take unilateral and destabilizing measures," Stoltenberg said in a message on the social network Twitter.
Following a phone call with EU foreign policy chief Josep Borrell, Kosovo's Prime Minister Albin Kurti tweeted: "It was emphasized that elected mayors will provide services to all citizens."
NATO peacekeepers deployed to Kosovo following their 1999 bombing campaign, which drove the Serbian army and security police off Kosovar soil, ending a brutal counter-insurgency campaign.
