The United Nations Trusteeship Council (French: Le Conseil de tutelle des Nations unies), one of the principal organs of the United Nations, was established to help ensure that trust territories were administered in the best interests of their inhabitants and of international peace and security. The trust territories—most of them former mandates of the League of Nations or territories taken from nations defeated at the end of World War II—have all now attained self-government or independence, either as separate nations or by joining neighbouring independent countries. The last was Palau, formerly part of the Trust Territory of the Pacific Islands, which became a member state of the United Nations in December 1994.