JOHANNESBURG (WASHINGTON POST, BLOOMBERG) - Former US president Barack Obama lamented the rise of "strongman politics" and "the utter loss of shame" among political leaders who repeatedly lie during a speech on Tuesday in South Africa that was widely seen as aimed in part at his successor.

Speaking at an event honoring the late Nelson Mandela ahead of the 100th anniversary of his birth, Obama did not mention President Donald Trump by name and cast his concerns far more broadly, warning against movements toward authoritarianism globally.

But Obama made several remarks that came across as thinly veiled criticism of Trump, who during a summit in Helsinki just the day before appeared to place more trust in Russian President Vladimir Putin than in the US intelligence officials who concluded that Russia interfered in the 2016 U.S. election.

"I am not being alarmist, I'm simply stating the facts," Obama told a crowd of about 15,000 in Johannesburg.

"Look around - strongman politics are ascendant, suddenly, whereby elections and some pretense of democracy are maintained, the form of it, where those in power seek to undermine every institution or norm that gives democracy meaning."

"A politics of fear, and resentment" is building, Obama said in the speech in Johannesburg. "It's on the move at a pace that would have seemed unimaginable just a few years ago."

Obama's speech also contained criticism of stances Trump has taken on climate change, immigration and other policies.

"You have to believe in facts," Obama said. "Without facts there's no basis for cooperation. If I say this is a podium, and you say this is an elephant, it's going to be hard for us to cooperate."

"I can't find common ground if somebody says that climate change just isn't happening, when almost all the world's scientists tell us it is," Obama continued.

"I don't know where to start talking to you about this. If you say it's an elaborate hoax, where do we start?"

At a time when independent fact-checkers are calling out Trump about misleading and false statements almost daily, Obama also took aim at politicians who lie, as well as those who attack the news media, as Trump routinely does."People just make stuff up," he said.

"They just make stuff up. . . . We see the utter loss of shame among political leaders where they're caught in a lie and they just double down and they lie some more. It used to be that if you caught them lying, they'd be like, oh, man - now they just keep on lying."

Obama also lamented that "the free press is under attack" at a time when Trump routinely complains about his coverage by "the fake news."

"Social media, once seen as a mechanism to promote knowledge and understanding and solidarity, has proved to be just as effective promoting hatred and paranoia and propaganda and conspiracy theories," he added.

The former U.S. president suggested a different path."Let me tell you what I believe," he said.

"I believe in Nelson Mandela's vision. I believe in a vision shared by Gandhi and King, and Abraham Lincoln. I believe in a vision of equality and justice and freedom and multiracial democracy built on the premise that all people are created equal and are endowed by our creator with certain inalienable rights."

The trip is Obama's first to Africa since leaving office in early 2017. He stopped earlier this week in Kenya, where he visited the rural birthplace of his late father.

Mandela, who spent 27 years in prison and emerged to become South Africa's first black leader after white minority rule ended, died in December 2013 at the age of 95.

Obama praised the global icon's legacy, saying he had shown that people were bound together by a common humanity and that a world governed by democratic principles was possible.

Obama warned that advances made since Mandela was in office were being eroded, with far-right parties emerging in the West that advocate protectionism, closed borders and barely hidden racial nationalism.

Many developing countries are seeking to emulate China's model of authoritarian control combined with capitalism, he said.

"Strong-man politics is ascending suddenly whereby elections and some pretense of democracy are maintained, a form of it, but those in power seem to undermine every institution or norm that gives democracy meaning," Obama said.

"We now stand at a crossroads, a moment in time in which two very different visions of humanity's future compete for the hearts and minds of citizens around the world."

While there was no guarantee that progressive values would ultimately triumph, there was no place for despondency, Obama said.

"It's tempting right now to give into cynicism to believe that recent shifts in global politics are too powerful to push back," he said.

"We have to resist that cynicism."