How did the annexation of Bosnia-Herzegovina in 1908 increase tensions with Russia and Serbia?

The 1908 annexation of Bosnia and Herzegovina by Austria-Hungary significantly escalated regional tensions, contributing to the eventual outbreak of World War I.1

Impact on Serbia

Serbia was outraged by the annexation due to its close ethnic and geographic ties to the provinces. The Serbian government demanded that Austria-Hungary cede a portion of the territory to them. When Austria-Hungary, backed by Germany, threatened to invade if these demands persisted, Serbia was forced to back down, leading to deeply embittered relations between the two nations.1

Impact on Russia

The crisis also humiliated Russia. Although the Russian foreign minister, Aleksandr P. Izvolsky, had initially agreed not to object to the annexation in exchange for potential access to the Bosporus and Dardanelles straits, he was unprepared for the speed of the Austrian action. Faced with intense domestic anti-Austrian sentiment and pressure to support Serbia, Russia was forced to back the Serbian claims. Ultimately, lacking sufficient support from its ally France, Russia was compelled to accept the annexation, fostering deep resentment over having been deceived and humiliated.1