The UN elected Kofi Annan, its first black Secretary General, after criticisms that it had not been dealing with various crises in Africa.
Many commentators including Nelson Mandela spoke out about the change in the US attitude towards the UN after Annan was voted in.

Racism makes countries ignore UN: Mandela

"When the (UN) secretaries-general were white, we never had the question of any country ignoring the United Nations but now that we have got the black secretaries-general like...Kofi Annan, certain countries that believe in white supremacy are ignoring the United Nations," he [Nelson Mandela] told reporters at the airport on his arrival. "We have to combat that without reservation," he said.

The link is to a an article in the archives of The Daily Times (Pakistan).