Story highlights Obama said he recognized an "anger and fear in the American population"

Obama's final international trip takes him to Greece, Germany and Peru

Athens, Greece (CNN) President Barack Obama issued a warning Tuesday against "crude nationalism" in the wake of Donald Trump's victory, saying during a news conference on his final overseas trip that the President-elect had tapped into a "troubling" strain of rhetoric playing on Americans' fears of globalization to win the presidency.

Speaking in Athens, Obama said he recognized an "anger and fear in the American population" over threats of mechanization and globalization, but that Republican officials didn't use facts when making their case about the US economy.

"You've seen some of the rhetoric among Republican elected officials and activists and media. Some of it pretty troubling and not necessarily connected to facts, but being used effectively to mobilize people," Obama said at a news conference alongside Greek Prime Minister Alexis Tsipras. "And obviously, President-elect Trump tapped into that particular strain within the Republican Party and then was able to broaden that enough and get enough votes to win the election."

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Obama said countries across Europe, as well as the United States, were confronting populist movements based on a fear of intruding global forces, arguing people "are less certain of their national identities or their place in the world." He said leaders should heed lessons from results in the US and in Britain, which in June voted to exit the European Union.

"It starts looking different and disorienting. And there is no doubt that has produced populist movements, both from the left and the right," he said. "That sometimes gets wrapped up in issues of ethnic identity or religious identity or cultural identity. And that can be a volatile mix."

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