Kosovo celebrated the 20th anniversary of the deployment of NATO troops in an operation that helped stop a Serb military crackdown on ethnic Albanians that left more than 10,000 dead.
Former US President Bill Clinton, ex-Secretary of State Madeleine Albright and ex-NATO commander Wesley Clark were joined by other world leaders in the capital, Pristina on Wednesday.
Cheered by a crowd of 3,000 in central Skenderbeu Square, Clinton said it had been "my life's biggest honour to have stood with you against ethnic cleansing and for freedom."
Kosovo's 1998-99 war ended with a 78-day NATO air campaign.
It declared independence from Serbia in 2008, but Belgrade does not recognise it and relations remain tense.