PRISTINA, Kosovo — The decision to transform Kosovo’s security force into an army is “irreversible,” the country’s president said Sunday, while offering assurance that a new national military does not threaten ethnic Serbs living in the former Serbian province.

President Hashim Thaci gave a briefing on the army plan before he left for New York, where the United Nations Security Council is expected in the coming days to discuss the small Balkan nation’s decision.

Kosovo's parliament overwhelmingly approved the army's formation Friday. Neighboring Serbia has warned that an army in a place it considers Serbian territory could result in an armed intervention.

"Whatever happens at the Security Council, despite the concerns of a certain individual or a country, the formation of the Kosovo army is an irreversible act," Thaci said.

Serbia does not recognize Kosovo’s 2008 declaration of independence. Its government insists the army would violate a U.N. resolution that ended Serbia’s crackdown on Kosovar separatists from 1998-1999.

Serbia’s foreign minister, Ivica Dacic, reiterated Sunday that Belgrade will insist at the U.N. Security Council session that the army was formed in violation of the resolution.

"It is important that the position of Serbia will be heard," Dacic said.

Serbia's government has warned it might use its own military to respond, with Prime Minister Ana Brnabic saying that's "one of the options on the table." An armed intervention by Serbia could bring a confrontation with the NATO-led peacekeepers stationed in Kosovo since 1999.

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The U.N. Security Council held closed consultations late Friday on the format of a meeting on the dispute. Russia, Serbia’s close ally, wants the council to meet publicly, and European nations have sought a closed session.

NATO's chief has called Kosovo's action "ill-timed." The United States has expressed support for "Kosovo's sovereign right" as an independent nation that unilaterally broke away from Serbia.

Thaci said the army would be a professional and multiethnic one, with 5 percent of the troops coming from the ethnic Serb minority; he advised Serbian President Aleksandar Vucic to take a cue from Serbs residents in Kosovo “who feel calm and who take part in the army.”