It is neccessary to focus on the fluctuating American policy towards South Africa to explain the American attitude. Before the Second World War South Africa did not exist for Americans but gradually after that Americans became aware of South Africa. However disillusionment with the country mounted as apartheid took shape. Different administrations had different foreign policies. America was not without its fair share of problems and had a sense of affinity for South Africa as the racial equality and human rights issues in South Africa showed parallel lines to the American issue before their commitment to right what is wrong.
