This chapter investigates Western Balkan security dynamics by applying structural realism to analyze how the security dilemma arises from regional arms procurement and military modernization. The study examines the historical development from the violent disintegration of Yugoslavia to today’s arms dynamics, illustrating how unresolved conflicts and existing questions of statehood continue to shape regional security perceptions. Serbia stands out as the leading military power in the region, having implemented a multi-vector procurement approach to maintain relations with Russia, China, and Western suppliers. Croatia has aligned its military modernization efforts with NATO standards as a member of the alliance. Russia and China utilize arms transfers, combined with political backing and economic influence, to exploit regional weaknesses that hinder the progress of Euro-Atlantic integration. The 1996 Florence Agreement does not solve the existing arms control problems in the region, as advances in military technology, corruption in defense procurement, and criminal networks for arms trafficking continue to pose significant obstacles. The analysis reveals that existing security challenges necessitate enhanced transparency measures, updates to arms control agreements, and confidence-building initiatives to reconcile the security positions of countries in this region.