The world has changed significantly since the founding of the United Nations and so have its conflicts. During the mid-twentieth century, the pre-eminent challenge for multilateral cooperation was the awesome prospect of a Third World War. Today, in the aftermath of the Cold War, we see a more elaborated focus on the prevention of conflict and the protection of communities and peoples—both as a sovereign responsibility of the modern nation-state as well as a central focus of the United Nations peace engagements.