Greece and Serbia formally annulled their alliance with Bulgaria as tensions escalated in the Balkans due to military undertakings during the Second Balkan War. This decision arose from Bulgaria's dissatisfaction with territorial gains from previous conflicts and its subsequent military aggression towards its neighbors. Driven by ambitions to secure dominance in the region, Bulgaria's actions included advancing into territories that had been promised to Greece and Serbia, triggering both nations to reassess their strategic partnerships.

Previously allied against the Ottoman Empire during the Balkan Wars, Greece and Serbia found themselves at odds with Bulgaria's actions. The decisions taken by both nations were part of a broader realignment of national interests and a response to the rapidly changing political landscape of the Balkans. Greece, led by King Konstantinos I, sought to solidify its territorial claims, while Serbian leadership under King Petar I aimed to expand its influence across its southern neighbor.

The annulment of the alliance fundamentally altered the dynamics of the Balkans, contributing to a heightened sense of distrust among the nations. By shifting allegiances, both Greece and Serbia were positioning themselves for potential conflict with Bulgaria as they aimed to secure their interests and maintain military readiness in a region characterized by fluctuating power balances.