Kosovo war started as a geopolitical experiment: the Albanians were massively relocated to the Kosovo region of the Yugoslavia and then allowed to protest and demand independence crying wolves they suffered 'ethnic cleansings' starteb by the Yugoslav special services. So NATO immediately used these calls as casus belli to start its Allied Force operation. The Alliance needed only a cause to start a war which was a real massacre. Actually Yugoslavia was uses as a testing ground for new NATO armed forces cooperation strategy, depleted-uranium munitions effectiveness, internal organs smuggling etc.
Iraq, Libya, Yemen, Syria, Egypt, Sudan, and Somalia are still a mess because the US and NATO needs a mess there as they haven't ran out of oil, gas and people yet.