Lesotho became a UN member on 17 October 1966 and participates in ECA and all the non-regional specialized agencies except IAEA and IMO. A Commonwealth member, Lesotho also takes part in the African Development Bank, G-77, and AU. The nation is a member of the WTO, as well as a signatory to the Law of the Sea. . The country's close relationship with South Africa is a major factor in its economic survival. Lesotho belongs to a customs union with South Africa, Botswana, Swaziland, and Namibia. Lesotho is a signatory to the Lomé Convention and a member of the nine-nation Southern African Development Community (SADC).