Serbs were pro-Russian and numerous. They were thus mostly Yugoslavian majority. This bothered the United States, which went to war with Yugoslavia in 1999.
The Serbs wanted to keep Yugoslavian unity going to war against the secessionists. This mistake was fatal for the Serbs since the United States asked them to let the UN take care of Kosovo when it had been annexed by Serbs, an impossible agreement to pass for Serbs. So European countries like Spain will not recognize Kosovo.
The Serbs kill was invented by the United States’ diplomacy. Germany then launches the media manipulation, followed by France with Le Monde, then Le Figaro. England and Russia will follow the manipulation. After, an air war is launched against Serbs, causing 140,000 deaths because civilians were targeted.