South Africa has played a key role as a mediator in African conflicts over the last decade, such as in Burundi, the Democratic Republic of Congo (DRC), the Comoros, and Zimbabwe. After apartheid ended, South Africa was readmitted to the Commonwealth of Nations. The country is a member of the Group of 77 and chaired the organisation in 2006. South Africa is also a member of the Southern African Development Community (SADC), South Atlantic Peace and Cooperation Zone, Southern African Customs Union (SACU), Antarctic Treaty System (ATS), World Trade Organization (WTO), International Monetary Fund (IMF), G20, G8+5, and the Port Management Association of Eastern and Southern Africa.