Some of the ongoing international armed conflicts – in particular, one against ISIS, and those in Syria and Ukraine – are testing the very architecture of international conflict and security law. They are revealing new challenges to both the jus ad bellum and jus in bello, some of which are so grave as to suggest international institutions’ lack of capacity in dealing with them appropriately. The Chapter calls for the emergence of a more integrated international law based upon universal values, including upon values of Islamic international law, for a better maintenance of international peace and security. It also introduces the notion of patriacide – an extreme form of aggression aimed at destroying a State’s constitutional, political, economic and technical organization – and calls for a broader implementation of the crime of aggression at the domestic level.