The United States, whose failure to join the League of Nations was a major cause of the failure of that body, is a charter member of the UN, having joined on 24 October 1945. The United States participates in ECE, ECLAC, ESCAP, and all the nonregional specialized agencies (it withdrew from UNESCO in 1984, charging the agency with mismanagement and with bias against Western nation, but rejoined in 2002). There are also policy differences between the United States and several other UN agencies. The US share of the total funds required for the upkeep of the UN is about 25% of the total, far more than any other nation; however, the United States withheld its payments during the 1990s. The US participates in more than 70 intergovernmental organizations, including the Asian Development Bank, OECD, the IMF and IBRD (World Bank), and international councils and commissions on various industries. The US also participates actively in the Permanent Court of Arbitration. Hemispheric agencies include the Inter-American Committee on the Alliance for Progress, IADB, and OAS.
NATO is the principal military alliance to which the United States belongs. The ANZUS alliance was a mutual defense pact between Australia, New Zealand, and the United States; in 1986, following New Zealand's decision to ban US nuclear-armed or nuclear-powered ships from its ports, the United States renounced its ANZUS treaty security commitments to New Zealand. The nation is a member of the WTO but refused to sign the Law of the Sea because of unwillingness to relinquish rights over seabed mining; in keeping with international practice, however, the United States does maintain a 200-mi coastal economic zone. In 1992, the United States, Canada, and Mexico signed the North American Free Trade Agreement (NAFTA), creating a free-trade zone among the three countries. It was ratified by all three governments in 1993 and took effect the following year. In 1986, the United States approved the 1948 UN convention against genocide.