Security in the Western Balkans has recently deteriorated due to heightened geopolitical tensions, EU enlargement fatigue and democratic backsliding. Despite some positive developments, Bosnia and Herzegovina remains unstable, and the Belgrade/Pristina dialogue is still deadlocked. In addition, all Western Balkan states have increased their defence budgets and have engaged in military modernization. At the same time, policymakers and the media in the region often evoke the spectre of military competition and an arms race. This Policy Brief shows that, although the letter of the Agreement on Sub-Regional Arms Control signed in Florence in 1996 is still being complied with, these developments have already eroded trust in the region. If allowed to unfold, they could lead to further escalation in the future.