U Thant was appointed to a second term as Secretary-General of the United Nations by the General Assembly on December 2, 1966 on the unanimous recommendation of the Security Council. His term of office continued until December 31, 1971, when he retired. During his time in office, he oversaw the entry into the UN of dozens of new Asian and African states and was a firm opponent of apartheid in South Africa. He also established many of the UN's development and environmental agencies, funds and programmes, including the United Nations Development Programme (UNDP), the UN University, UNCTAD, UNITAR and the United Nations Environment Programme.