He compared the president to Russian strongman Vladimir Putin, saying Trump also would like to create a "mafia state" that suppresses individual rights. He can't "because the Constitution and the institutions and a vibrant society won't allow it."
Soros said he is using his foundation and the billions at his disposal to "protect the democratic achievements of the past." Soros was an active supporter of Hillary Clinton during her unsuccessful campaign against Trump in 2016. He reportedly had lost about $1 billion when the market surged higher after Trump's victory.
"Not only the survival of open society but the survival of our entire civilization is at stake," he added. "The rise of leadership such as Kim Jong Un in North Korea and Donald Trump in the United States have much to do with this."
To head off a nuclear crisis, Soros recommended a "carrot and stick" approach in which North Korea is rewarded for "suspending further development of nuclear weapons."
As for the U.S., Soros said he will be mobilizing his own political forces to try to defeat Trump.
"Clearly I consider the Trump administration a danger to the world," he said. "But I regard it as a purely temporary phenomenon that will disappear in 2020 or even sooner."
Soros said he sees trouble all over the world and even in cyberspace, where social networks are invading people's lives and in some cases ruining them as well.
"The distinguishing feature of internet platforms is that they are networks and they enjoy rising marginal returns," he said. "They deliberately engineer addiction to the services they provide. This can be very harmful, particularly to adolescents."
And he expressed worry about the European Union's future, saying that the bloc is "in a revolutionary period" where Russia again has arisen and the EU is in disarray.