South Africa became a charter member of the UN on 7 November 1945 and has technically remained a member, despite continued disputes with the world body over apartheid and the country's unwillingness to place its League of Nations mandate, Namibia, under UN international trusteeship. After the UN General Assembly put the apartheid issue on its agenda, South Africa retained only token representation at the UN from 1955 to 1958. In 1966, the Assembly terminated South Africa's mandate over Namibia; in 1971, the International Court of Justice issued an advisory opinion holding that South Africa's presence in Namibia was illegal. On separate occasions in 1974, 1979, and 1980, South Africa attempted to participate in the General Assembly's meetings, but each time the Assembly prevented the South African delegation from taking its seat; however, resolutions to expel South Africa from the UN have been vetoed in the Security Council by the UK, United States, and France. South Africa agreed in principle in 1978 to permit elections in Namibia that would lead to the territory's independence, which was gained in 1990. The nation adheres to the Law of the Sea and belongs to the WTO.
South Africa has reestablished membership in the ECA, IMF, and the World Bank. South Africa sent token forces to serve with the UN in Korea and has contributed funds to the Office of the High Commissioner for Refugees and to UNICEF. South Africa also belongs to the IAEA, ICAO, IDA, IFC, ITU, UPU, WHO, and WIPO.
A founding member of the Commonwealth of Nations, South Africa withdrew on 31 May 1961 as a result of objections by nonwhite members to its membership, but later rejoined the organization. South Africa is joined in a customs union (SACU) with Botswana, Lesotho, Swaziland, and Namibia. Originally, the three smaller lands were to have been transferred to South African control, but the plan was dropped by the British after South Africa left the Commonwealth, and the three subsequently became independent.
The nation was diplomatically isolated from other states on the African continent after Angola, Mozambique, and Zimbabwe were constituted as black-ruled countries during 1975–80, leaving South Africa as the continent's only white-minority regime. South African teams were excluded from international competition, such as the Olympic Games (from 1960). Following changes in South Africa's political situation, the country was reinstated to international competition by the International Olympic Committee. South Africa sent a team to the 1992 Winter and Summer Olympics. It also now is a member of the African Union (AU) and the sub-regional organization of the Southern Africa Development Community (SADC).