Why did the hostility between austria-Hungary and Serbia intensify?

The hostility between Austria-Hungary and Serbia intensified due to rising nationalist sentiments and ethnic tensions in the Balkans. The assassination of Archduke Franz Ferdinand by a Bosnian Serb nationalist in June 1914 exacerbated the situation, leading Austria-Hungary to view Serbia as a direct threat to its stability. This event triggered a series of diplomatic crises and ultimatums, ultimately contributing to the outbreak of World War I. Additionally, Serbia's desire for greater influence in the Balkans clashed with Austria-Hungary's ambitions, further deepening the animosity between the two nations.