Tensions soared in the Balkans a day before Kosovo is set to approve the formation of an army, with Serbia warning Thursday that the move would threaten peace in the war-scarred region, AP said. Kosovo’s Parliament is expected to pass legislation on Friday turning an existing 4,000-strong security force into an expanded, lightly armed army. After talks with the head of the UN mission in Kosovo, Serbian President Aleksandar Vucic described Kosovo’s decision as a “new provocative and one-sided measure.” The plans have raised Belgrade’s concerns for the future of Serbs in Kosovo. Serbia will “do its best to preserve peace and stability,” Vucic said, but warned the “situation will be considerably worsened” if Kosovo goes ahead with the decision on Friday. Serbia alleges that the army’s main purpose is to ethnically cleanse Kosovo’s Serbian-dominated north, a claim strongly denied by Pristina.