Scholars and practioners of International relations have devoted attention to prevent arms-race. In recent years, the United Nations then, World Bank, United States and other governments have revamped their institutional architecture for addressing prevention in Arm-race for peace-building. The relationship between weak states and durability of arms race has acquired new emphasis in IR research. This article analyzes recent conceptual developments in prevention of arms-race, for peace building relating them to new thin king. It then analyzing international architecture for addressing prevention in arm-race, helpful in peace building and analyzing likely policy challenges in the near future. We argue that despite important analytic insights and institutional changes serious challenges persist in effort to prevent war from recurring.