(CNN) -- Kosovo's declaration of independence from Serbia in February 2008 was legal, the International Court of Justice ruled in a 10-4 vote Thursday.
There were celebrations in Pristina, with fireworks being set off in the capital of Kosovo after the finding was announced, journalist Vlora Rrustemi told CNN.
But Serbia's Foreign Minister Vuk Jeremic expressed disappointment, saying Belgrade had hoped for a "peaceful compromise solution" that did not create "dangerous secessionist precedents" elsewhere in the world.
The U.N. General Assembly asked the court to clarify the legality of Kosovo's declaration of independence, based on a request from Serbia, and the court held hearings last December.
Serbia maintains Kosovo's move for independence was illegal and that it remains a part of the Serbian republic.
U.S. Vice President Joe Biden called the president of Serbia before the court made its announcement, the White House said.
Biden told Boris Tadic that Washington fully supports "a democratic and multi-ethnic Kosovo, and he reiterated the United States' unwavering commitment to Kosovo's sovereignty and territorial integrity," the administration said.
He urged Serbia to work with Kosovo to resolve their problems, and also "affirmed the strong and deep ties between the United States and Serbia."
Thursday's verdict was not legally binding. It's an advisory opinion, not a judgment, a court spokeswoman said. The United Nations General Assembly therefore remains free to decide what action to take.
Such opinions still carry great legal weight, however, and Thursday's verdict could set the tone for Kosovo's relations with other countries.
The court considered written statements from 36 U.N. member states, including Serbia, along with Kosovo.
Since the declaration of independence, many countries, including the United States and United Kingdom, have recognized Kosovo as an independent state. Many countries -- such as Russia, China, neighboring Bosnia, and the European nations of Spain and Greece -- have not, however.
The court's opinion could also encourage other separatist regions to declare independence.
The General Assembly made its request for clarification after Serbian President Boris Tadic told members that Kosovo's "unilateral, illegal, illegitimate" move meant "the very nature of the international system has been called into question."
Serbia then put forward a resolution to ask the International Court for an advisory opinion, and member states voted overwhelmingly in favor of it in October 2008.
CNN's Richard Allen Greene and Matthew Chance contributed to this report.