This chapter examines the effect of nuclear weapons on the international system from two complementary points of departure. It discusses the general place of violence in international relations: what its functions in the present period are and what the influence of nuclear weapons on the role of violence is. The chapter characterizes nuclear peace and its attendant problems. The principal aim in the establishment of the League of Nations after World War I, and the founding of the United Nations after World War II, was in fact the prevention of war. The covenant of the League of Nations obligated its members to seek peaceful solutions to their conflicts through such means as negotiation, arbitration, and adjudication. Nuclear peace is at present not a general phenomenon, but is limited to the great powers and is of partial application. If there is peace today in other sections of the world, it is a non-nuclear peace.