Nato said today it would deal firmly with any violence in Kosovo after the breakaway province declared independence from Serbia and that all parties involved needed to show restraint.
The military alliance said it would continue to provide security in Kosovo, where some 16,000 troops - including 300 Irish personnel - serve in the Nato peace force KFOR.
Serbia's leaders immediately rejected Kosovo's "unilateral and illegal" declaration of independence, but said they would not use force to reclaim it.
"During this sensitive period, KFOR will respond swiftly and firmly against anyone who might resort to violence in Kosovo," Nato Secretary-General Jaap de Hoop Scheffer said in a statement, urging all parties involved to exercise "the maximum restraint and moderation".
"All parties should recognise that KFOR will continue to fulfil its responsibility for a safe and secure environment throughout the territory of Kosovo ... unless the (UN) Security Council decides otherwise," he said.
"KFOR will continue to provide security for all citizens of Kosovo, majority and minority alike, in an impartial manner, just as before," Mr de Hoop Scheffer added. Nato ambassadors will meet tomorrow to assess the situation, the statement said.
Russia urged the United Nations to annul Kosovo's declaration of independence, claiming it was illegal and could cause an escalation in ethnic violence in the region.
Russia warned the US and European Union against creating a "serious precedent" by recognizing Kosovo.
Russia called for an emergency meeting of the UN Security Council later today and backed Serbia's "just demands" for the restoration of its territorial integrity, the Foreign Ministry said in a statement.
"We expect the UN mission and Nato-led forces in Kosovo to take immediate action to carry out their mandate ... including the annulling of the decisions of Pristina's self-governing organs and the taking of tough administrative measures against them," the ministry said.
The United States said it notes that Kosovo's declaration and welcomed the government's commitment to implement UN provisions to protect ethnic minority communities.
In a statement that stopped short of recognizing Kosovo's independence, the State Department said: "The United States is now reviewing the issue and discussing the matter with its European partners." It called on all parties to "exercise the utmost restraint and to refrain from any provocative act."
The State Department said the US welcomed the Kosovo's government's clear commitment to implement provisions of the plan developed by United Nations special envoy Martti Ahtisaari to protect ethnic minority communities.
The EU, which yesterday endorsed a police mission to Kosovo, will meet tomorrow to discuss the secession.
The Vatican called for "prudence and moderation" in Kosovo and Serbia and urged politicians in the region to show "a decisive and concrete commitment to ward off extremist reactions and violence".
"The Holy Father continues to look with affection at the people of Kosovo and Serbia, is close to them and is praying at this crucial moment of their history," a statement said.