NATO, the European Union and the United States urge restraint amid tensions between Serbia and Kosovo

The United States, NATO and the European Union have called for maximum restraint in northern Kosovo, where authorities closed a third border crossing on Wednesday and tensions rose with local Serbs over its independence in 2008.

For more than 20 years, Kosovo has been a source of tension between the West, which has supported its independence, and Russia, which supports Serbia in its efforts to block Kosovo’s membership in international organizations including the United Nations.

“We call on everyone to exercise maximum restraint and take immediate action to unconditionally de-escalate the situation and refrain from provocations, threats or intimidation,” the European Union and the United States said in a joint statement.

NATO’s mission in Kosovo, KFOR, said it supported dialogue between all parties to defuse tensions, including Serb roadblocks on main roads with trucks and other heavy vehicles and violent clashes with police.

Serbia put its army on high alert on Monday.

For its part, the Kremlin has denied Kosovo’s allegations that Russia is exerting influence on Serbia to destabilize Kosovo, saying that Serbia is defending the rights of Serbs.

A former Kosovo Serb police officer whose arrest sparked violent protests by Kosovo’s Serb minority has been released and placed under house arrest at the request of the prosecutor’s office, a spokesperson for the Pristina First Instance Court told Reuters.

Dejan Pantic was arrested on December 10 for assaulting a police officer who has been on the job ever since when Serbs in northern Kosovo exchanged gunfire with police and set up more than 10 roadblocks demanding his release.

The court’s decision angered Kosovo government officials, including Prime Minister Albin Kurti and Minister of Justice Albolina Hakshaw.

“I don’t know how to understand that and how someone accused of such a serious terrorism-related crime can go to house arrest,” Hackshaw said.

“I’m curious as to who is the prosecutor who made this request, and who is the preliminary trial judge who agrees with it,” Curti said.

Pantik was one of many Serbs who left the police and other institutions after Pristina said it would implement a law requiring Serbs to cancel license plates for cars issued from Serbia that dated before the 1998-1999 guerrilla uprising that led to Kosovo’s independence.

Serbian President Aleksandar Vucic has urged Serbs in Kosovo to end protests against the Pristina government and assure them they will be immune from prosecution, a Serbian official said on Wednesday.

Petar Petkovic, the head of the Serbian government’s office for Kosovo, said Vucic and Serbs from northern Kosovo would meet later on Wednesday and announce whether the barriers would be removed.

Serbs in northern Kosovo, who believe they are still part of Serbia, are resisting any moves they see as anti-Serb.

Two border crossings between Serbia and Kosovo were closed on December 10, and a third, the largest for road freight, Merdere, was closed to traffic on Wednesday, disrupting flights for Kosovars working elsewhere in Europe from returning home for holidays.

Kosovar Interior Minister Çelal Svekla said on Tuesday that Serbia aims to destabilize Kosovo. Serbia says it only wants to protect the minority there.

About 50,000 Serbs living in northern Kosovo refuse to recognize the government in Pristina or Kosovo’s status as a separate state. They have the support of many Serbs in Serbia and its government.

Albanian-majority Kosovo declared independence with Western support, following the 1998-1999 war in which NATO intervened to protect Albanian citizens.