After a Civil War developed in Kosovo and the Yugoslav army intervened, the US and NATO intervened to stop end the war. The US and NATO heavily bombed Yugoslavian forces and they acceded to NATO demands.
A Civil War developed in Kosovo where ethnic Albanians pushed for independence. The Yugoslav army tried to put down the KLA who was fighting for independence. In the course of the fight, the Yugoslavian enacted both ethnic cleansing and mass murder. As a result, the United Nations adopted a series of resolution that resulted in the activation of NATO forces. This initially forced the Yugoslavs to agree to the entry of observers. Despite the observers, the Yugoslav forces continue to commit atrocities such as 1999 the Račak massacre when "45 Kosovan Albanian farmers were rounded up, led up a hill and massacred.
There was a peace conference held at the Château de Rambouillet, outside Paris. When those talks failed because the Yugoslavs refused to go along with the terms negotiated, the matter was turned over to NATO to reach a military solution.
On March 24, 1999, NATO began a bombing campaign against Yugoslavia. The NATO demand- that their troops leave Kosova replaced by peacekeepers. NATO flew 38,000 combat mission over Yugoslavia in ten weeks. The air campaign attacked individual Yugoslav units as well as strategic targets. However, it seemed it was not able to convince the Yugoslavs to withdraw. NATO member states began to threaten to send ground troops in. That was enough to satisfy the Yugoslavs to accept the peace terms offered by NATO. On June 10th NATO and Yugoslavia both agreed to the terms, and Yugoslav troops began withdrawing. The first NATO troops to enter Kosova were Norwegian Special forces on June 12th. The US 1 Armored Division were the first US forces to enter the country