Although the first requirement for the present stability in Europe arose with the end of World War II, the signing of the Treaty establishing the European Coal and Steel Community in 1951 cemented the peace. The institutionalization of cooperation in one essential sector not only created new opportunities for confidence-building measures towards peace and stability but also formed the basis of regional integration in Europe. The post-war political climate in Europe allowed the energy sectorcoal and steel production- to be placed under a supranational authority. Such a functional cooperation also necessitated the interconnection of various economic sectors, which led to the integration in one policy area spilling over into others.
The process that started with the signing of the treaty advocating integration of the energy sector in Western Europe constituted a historic milestone in regional integration in Europe, since the European Union today stands alone as the most advanced example of regionalism in the world.