SKOPJE, North Macedonia (AP) — Albanian Prime Minister Edi Rama urged NATO on Wednesday to further boost its military forces in Kosovo and secure the country’s borders with Serbia, warning that recent ethnic violence in Kosovo could potentially trigger a wider Balkan conflict.

Kosovo’s border with Serbia was “out of control,” Rama said after an informal meeting of Western Balkan NATO members in North Macedonia.

He said the frontier was being used for a host of illegal activities, including drugs and arms smuggling and infiltration by ultra nationalists, that could lead to “great disturbances” in the region.

Kosovo, which has an ethnic Albanian majority, is a former Serbian province. It gained independence with the help of a NATO military campaign, launched in 1999 to end a bloody Serb crackdown on an armed separatist movement.

Tensions remain high, with violence breaking out twice in recent months, and Western countries fear that Russia could try to foment trouble in the Balkans to avert attention from the war in Ukraine.

NATO Secretary-General Jens Stoltenberg, who attended the meeting in North Macedonia’s capital, Skopje, insisted after Wednesday’s talks that NATO doesn’t see any military threat to its allies in the Western Balkans.

“But what we do see is an increase in tensions, especially in Kosovo,” Stoltenberg said.

He said that NATO has strengthened its military presence in Kosovo — established after the 1999 bombing campaign against Serbia — with about 1,000 additional troops and heavier weaponry.

“We are cautious, of course. We are closely monitoring the situation and we will certainly do what is necessary to protect and defend our allies,” Stoltenberg said.

During a visit to Kosovo on Monday, Stoltenberg said that NATO was considering deploying additional peacekeeping troops there. On Tuesday in Belgrade, he said that the recent violent outbreaks in Kosovo were unacceptable and perpetrators must be brought to justice.

In May, Serb demonstrators in northern Kosovo clashed with NATO peacekeeping troops. In September, a Kosovo police officer and three Serb gunmen were killed in a shootout after about 30 masked men opened fire on a police patrol near the Kosovo village of Banjska.

Serbia doesn’t recognize Kosovo’s formal declaration of independence in 2008. Both countries want to join the European Union, which is mediating a dialogue between the former foes. Brussels has warned both that refusal to compromise jeopardizes their chances of joining the bloc.

Wednesday’s talks in Skopje were attended by Rama, the prime ministers of North Macedonia and Montenegro, Dimitar Kovačevski and Milojko Spajić, as well as Croatian President Zoran Milanović.