In World War I, no strong nations remained on the sidelines to give effective backing to international law, and the concept of third party arbitration was again endangered; many of the standing provisions of international law were violated. New modes of warfare presented new problems in the laws of war, but attempts after the war to effect disarmament and to prohibit certain types of weapons (see war, laws of) failed, as the outbreak and course of World War II showed. The end of hostilities in 1945 saw the world again faced with grave international problems, including rectification of boundaries, care of refugees, and administration of the territory of the defeated enemy (see trusteeship, territorial). The inadequacy of the League of Nations and of such idealistic renunciations of war as the Kellogg-Briand Pact led to the formation of the United Nations as a body capable of compelling obedience to international law and maintaining peace. After World War II, a notable advance in international law was the definition and punishment of war crimes. Attempts at a general codification of international law, however, proceeded slowly under the International Law Commission established in 1947 by the United Nations.