The next global epidemic is likely around the corner—and no amount of U.S. retrenchment from globalization will halt that outbreak at the U.S. border.

“There is a real reason for us to be scared of the idea of facing this threat with Donald Trump in the White House,”said Ron Klain, who served as President Obama’s Ebola czar, at the Spotlight Health Festival, which is co-hosted by the Aspen Institute and The Atlantic. Klain said the “president is anti-science” and “trades in conspiracy theories.”

“All those things would lead to the loss of many lives in the event of an epidemic in the United States, where we need the public not to trade in conspiracy theories, not to believe that the news was fake, but to respect scientific expertise,” said Klain, a veteran Democratic operative who served in both the Clinton and Obama administrations.

Klain added that Trump’s isolationist mindset has led to the United States pulling back from its leadership role in global health crises, which, he said, “is ... going to be a serious threat to our security.” Klain called Trump’s policies and views “xenophobic, if not racist,” leading to the blaming of immigrants and foreigners for problems that need public-health interventions.