In his General Assembly address, Serbian President Boris Tadic strongly criticized Kosovo's Unilateral Declaration of Independence (UDI) and countries that have recognized it, saying, "Kosovo's UDI is an attempt to impose a 19th-century outcome to a 21st-century challenge." Serbia has challenged the UDI in the International Court of Justice and Tadic took the opportunity to warn of the slippery slope that could result if the court rules in Kosovo's favor:
There is no doubt that the court's conclusions will constitute a powerful legal precedent, with over-arching consequences for the United Nations system. The outcome will either strongly deter other separatist movements from attempting to secede, or produce a result that could encourage them to act in similar fashion. Plainly said, should Kosovo's UDI be allowed to stand, a door would open for challenging the territorial integrity of any UN member State.
Tadic vowed that Serbia would "never, under any circumstances" recognize the indpendence of what he calls "our Southern province."
Never is an awfully long time, and given that Serbia is thankfully unwilling to use force to resolve the issue, it seems unlikely that they will be able to keep up this hardline stance as Kosovo's de fact independence becomes more established.