The NATO said today that it is ready to send more troops to northern Kosovowhere dozens of people have been injured in violent incidents this week, while the Pristina and Belgrade they exchanged accusations to ignite tensions in the region.

Unrest intensified in the region after the April elections, which Serbs boycotted, giving victory in four Serb-majority municipalities to ethnic Albanian candidates, who make up 90% of Kosovo’s population.

The fact that they took office last week despite receiving just 3.5% of the vote drew criticism from the United States, a staunch supporter of Kosovo’s declaration of independence from Serbia in 2008. As a result, Washington barred Pristina from an exercise of NATO.

The European Union said it would continue to talk to both sides.

“NATO will remain vigilant,” NATO chief Jens Stoltenberg said on the sidelines of a NATO summit in Oslo. “Our message to Belgrade and Pristina is that they must engage in good faith in the dialogue organized by the EU.”

He said the alliance was ready to send more troops on top of the 700 already on the way to bolster the existing force of 4,000 peacekeepers in Kosovo after 30 peacekeepers and 52 Serb protesters were injured on Monday.

The Serbs, who make up the majority in northern Kosovo, have never accepted Kosovo’s declaration of independence from Serbia in 2008, and still consider Belgrade their capital more than two decades after the Kosovo Albanian uprising against Serb rule.

Serbia needs to come to terms with its past, Kosovo President Viosa Osmani told Reuters on the sidelines of a European summit in Moldova, accusing Belgrade of destabilizing Kosovo by supporting “criminal gangs” in the north.

In remarks upon his arrival at the summit in Moldova, Vucic said Kosovo should withdraw “so-called mayors” in four municipalities and said such a step would help ease tensions.

Serbs living in northern Kosovo are demanding the implementation of an agreement brokered by the European Union in 2013 to create a union of autonomous municipalities in their region.

In the northern town of Leposavic, NATO soldiers have been guarding the town hall where one of the four newly elected mayors has been since Monday, Serbian protesters gathered outside the building, which is surrounded by barbed wire and raised the Serbian flag over a fence.

In the three other regions — Zubin Potok, Zvečan and North Mitrovica — the newly elected mayors do not work from their offices in the town halls, helping to maintain calm in these towns.

Kosovo declared independence nearly a decade after NATO bombing drove Serbia’s police and army out. Serbia and some 50,000 Serbs in northern Kosovo do not recognize Pristina and still consider Kosovo part of Serbia.