The clear-cut, unambiguous ruling contained little language from which the Serbian government can find solace.

"It is an upper cut right to the chin, with no moving around after that," an EU diplomat told Reuters.

Many observers had expected the International Court of Justice to present arguments that would give each side legal reasoning with

which to continue making their respective cases.

"The court opens the door for non-state actors to legally consider unilateral declarations of independence," said Mark Ellis, executive director of the International Bar Association who has worked on Kosovo issues in the past. "This will be a new and vexing challenge for the international community," he told Reuters.

Diplomats at the United Nations said the ruling underscored the clash between two cardinal principles dear to rank-and-file U.N. member states: self-determination, in this case for Kosovo's majority Albanians, and territorial integrity, in this case, Serbia's.

"It's not only the problem of Kosovo," one senior U.N. envoy said of Thursday's ruling. "It will be read in a lot of capitals on the basis not of the Kosovo case itself but of the general implications for each country."

"It's very difficult to guess what will be the reaction of the General Assembly," he added.

Edwin Bakker of the Clingendael Netherlands Institute of International Relations said the court's ruling was "bad news to a number of governments dealing with separatist movements."

"They may regard the ruling as a serious threat to their assumption that territorial integrity should be untouchable," he told Reuters, adding that the opinion would "strengthen separatists around the globe."

"If the eventual ruling affirms the right of unilateral self-determination, this may be a message for some future moves," Milorad Dodik, the prime minister of Bosnia's Serb Republic, said on Wednesday.

Dodik has repeatedly threatened a referendum for secession the Serb entity from Bosnia.