As Vijay Prashad points out, many of the world's leaders that are apparently mourning the death of Nelson Mandela were the "same people opposed [to] freedom in South Africa to the very end." 

Although Ronald Reagan has passed away himself, one can imagine he might salute Mandela today. But as president, Reagan worked against Mandela, so much so that he vetoed the Comprehensive Anti-Apartheid Act in 1986. Believing that he knew what was best for black people living under apartheid in South Africa, Reagan opposed sanctions and wanted to maintain friendly relations with the white supremacist government.

South Africa's Desmond Tutu disagreed. Watch this 1986 news report about Tutu's visit to the White House, in which Tutu explains the way that Reagan failed black South Africans.