The International Court of Justice says it will not hear accusations of genocide made against Nato nations by Serbia and Montenegro.
Nato planes targeted Belgrade during the 1999 campaign
Serbia accused Belgium, Canada, France, Germany, Italy, the Netherlands, Portugal and the UK of war crimes during the Kosovo conflict.
The case was brought in 1999 during Nato's bombing campaign against the then Federal Republic of Yugoslavia.
But the 15-judge panel at The Hague dismissed the claim unanimously.
The court ruled that the claim should be rejected because Serbia and Montenegro was not a member of the United Nations at the time.
The International Court of Justice is the United Nations' highest legal body to resolve disputes between nations.
Normally, it can only rule on disputes between UN member states, unless they have signed conventions giving the court jurisdiction or two states agree to let the court consider its dispute or if the UN Security Council refers a case for an advisory opinion.
Belgrade claimed the military intervention amounted to genocide as it was aimed at killing an ethnic group, the Serbs.
Nato launched its campaign to protect the ethnic Albanian population of Kosovo from attacks by Serb troops, but it was not authorised by a United Nations Security Council resolution.
The campaign group, Human Rights Watch, estimates that from March to June 1999 around 500 civilians were killed during the Nato bombardments.