Studies of U.S. government relations with Africa have generally focused on the role of the executive branch, specifically by examining and analyzing the views and activities of administration officials and the members of executive branch bureaucracies. This is only natural, given the predominant role that the executive branch has historically played in the development and implementation of U.S. policy toward the continent. However, the U.S. Congress has always played an important role in determining U.S. policy toward Africa due to its constitutional authority over the appropriation and authorization of funding for all foreign operations conducted by the executive branch. Furthermore, Congress enacted legislation on several occasions during the Cold War period that directly affected U.S. policy. For example, Congress approved the Clark Amendment prohibiting U.S. intervention in Angola (although it later voted to repeal the amendment) and also passed the 1986 Comprehensive Anti-Apartheid Act, which imposed sanctions on South Africa over the veto of the Reagan administration.