The U.S. counter-intelligence chief said on Tuesday he was worried about threats from China and Russia to disrupt the U.S. coronavirus vaccine supply chain.

Bill Evanina, director of the U.S. National Counterintelligence and Security Center, told an online Washington Post event that U.S. adversaries were trying to interfere with Operation Warp Speed, the U.S. government operation distributing the vaccines across the country.

"Our adversaries are trying to disrupt that supply chain," he said. Asked which adversaries he was particularly concerned about, he replied, "I would say China and Russia right now."