President Barack Obama is warning the world and America about a rising populism that he says is sweeping the planet, urging people to be vigilant about the future.

“We are going to have to guard against a rise in a crude sort of nationalism or ethnic identity or tribalism that is built around an ‘us’ and a ‘them,’” Obama said during a press conference in Greece.

He referred to World War I and World War II as the consequence of a rising sense of nationalism in Europe.

“We know what happens when Europeans start dividing themselves up and emphasizing their differences,” he said, calling the 20th century a “bloodbath” as a result.

He also warned Americans to be vigilant, citing the Civil War as a consequence of dividing the country “dangerously.”

“In the United States, we knows what happens when we start dividing ourselves along lines of race or religion or ethnicity,” Obama said. “It’s dangerous … we don’t realize our potential as a country when we’re preventing Blacks or Latinos or Asians or Gays or women from fully participating in the project of building American life.”

Obama said he believed that the world would be better off coming together and recognizing their common interests.

“So my vision’s right on that issue,” he said. “And it may not always win the day in the short term in any particular circumstance, but I’m confident it will win the day over the long term.”

Obama explained that many of the disruptions of the political status quo was a consequence of social media and political officials that were fueling the rise of populist anger.

He appeared frustrated by questions that suggested he missed the rise of frustration among the American people during his presidency.

“Of course I did,” he said.