The U.S. has become the most profound source of instability worldwide, Richard Haass, who is stepping down as president of the U.S. Council on Foreign Relations, said Friday.

After running the organization for two decades, Haass said he has come to a disturbing conclusion that the most serious danger to the world's security right now is the United States itself, he told The New York Times in an interview.

The unraveling of the American political system means that for the first time in his life, the internal threat has surpassed the external threat, he added.

Instead of being the most reliable anchor in a volatile world, the United States has become the most profound source of instability and an uncertain exemplar of democracy, Haass was quoted by the newspaper as saying.

"Our domestic political situation is not only one that others don't want to emulate ... But I also think that it's introduced a degree of unpredictability and a lack of reliability that's really poisonous. For America's ability to function successfully in the world, I mean, it makes it very hard for our friends to depend on us," he said.

After exploring other countries for most of the past half-century, Haass is ready to explore his own, as "the challenges at home have prompted a man who has spent his entire career as a policymaker and student of world affairs to turn his attention inward," said the New York Times.

The question is whether the U.S. has changed in the long run. "I should have a nickel ... for every non-American, every foreign leader who said to me: I don't know what's the norm and what's the exception anymore," said Haass.

Born in Brooklyn and raised on Long Island, Haass is a veteran of four administrations, one Democrat and three Republican, said the newspaper.

(Cover: A file photo of Richard Haass, U.S. foreign policy veteran. /CFP)