The Soweto riots of 1976, in which schoolchildren protesting the compulsory teaching of Afrikaans were gunned down, detained, and exiled, led the Security Council to impose a mandatory arms embargo on South Africa in 1977.
However, the Reagan and Thatcher governments, argued for 'constructive engagement' with, rather than isolation of, South Africa. This diminished the chances for more comprehensive sanctions on South Africa in the early 1980s.
A mass grassroots campaign under the direction of the Free South Africa Movement, headed by Randall Robinson, began to further isolate the South African regime. On 27 November 1984 250 people demonstrated outside the South African embassy in Washington in protest against apartheid and President Reagan's policy of constructive engagement. Other demonstrations like divestment campaigns, sit-ins, and College protests ultimately led to the passing of the Comprehensive Anti-Apartheid Act in 1986 over President Reagan's veto.
By this time South Africa was denied its seat in the United Nations, banished from participation in many international sports, and subject to an almost comprehensive worldwide sanctions campaign.
• Bouckaert, P. OverviewSouth Africa: The Negotiated Transition from Apartheid to Nonracial Democracy. wilsoncenter.org