Obama’s appearance comes one day after Trump’s joint news conference with Russian President Vladimir Putin in Helsinki, Finland, in which Trump sided with Putin over his own country’s intelligence on whether or not Russia interfered in the 2016 U.S. election.
>>Related: Trump-Putin summit: Trump takes Russia's side over intelligence community
Without mentioning Trump directly, Obama said politicians who push “politics of fear, resentment, retrenchment” are moving “at a pace unimaginable just a few years ago.”
He attacked “strongman politics,”saying that “those in power seek to undermine every institution ... that gives democracy meaning.”
He also added that “it’s a plain fact” that racial discrimination “still exists in the United States and South Africa.”
Obama added that the world’s governments and powerful elites were partially to blame for not delivering on its promises -- leaving countries on the brink of civil war.
That is why, Obama said, some of the world is “threatening to return to an older and more dangerous and more brutal way of doing business.”
Obama's speech honored the anti-apartheid leader and Nobel Prize winner by drawing on Mandela's powerful legacy of human rights, CNN reported.
Mandela was imprisoned for 27 years in his fight to end South Africa’s apartheid rule.
He was released in 1990 and became South Africa’s first black president.
Mandela died in 2013 at the age of 95.