Threats to international security have shifted from interstate conflict to more complex issues. States perceive new threats to security and try to respond to them either unilaterally or through international institutions. The process of defining new threats has emerged after the end of the Cold War, and several international organisations have tried to adapt their institutional mechanisms to face those challenges. The United Nations, as the main universal organisation dealing with peace and security, has also started this process. In December 2004, the Secretary General of the organisation delivered the Report entitled A more secure world: our shared responsibility. This article provides some reflections on relevant issues addressed in the Report.