This paper analyzes the relationship between the Republic of Serbia and the Republic of Kosovo after the NATO military intervention in 1999. It presents the historical context, including the Balkan Wars and the dissolution of the Socialist Federal Republic of Yugoslavia, which shaped the territorial and political dynamics of the region. The Balkan Wars resulted in territorial changes and rivalries within the Balkan Alliance, culminating in the Second Balkan War in 1913. Following the breakup of Yugoslavia, the NATO military intervention in 1999 had far-reaching political consequences, including the establishment of the UN Mission in Kosovo (UNMIK) and the withdrawal of Serbian forces from Kosovo. This intervention sparked debates about the right to humanitarian intervention and the use of force in international relations. After the NATO intervention, Serbia faced political crises, territorial loss, and economic problems. The relationship between Serbia and Kosovo remains tense, with differing visions of the future and difficulties in reaching normalization agreements. Kosovo declared independence in 2008, but Serbia does not recognize it. Serbia's relations with Russia and China further complicate the situation, suggesting that Serbia is gradually accepting the new situation. Issues such as the consequences of the Balkan Wars, the impact of the NATO intervention, and the challenges Serbia faced afterward are crucial to understanding the relationship between Serbia and Kosovo. The relationship between these two countries remains complex, with numerous obstacles to achieving lasting peace and stability. Despite these challenges, there are indications that Serbia is gradually accepting the new situation, albeit not openly.