U.S. Secretary of State Michael Pompeo said “enormous evidence” shows the novel coronavirus outbreak began in a laboratory in Wuhan, China, but didn’t provide any proof for his claims.

“I can tell you that there is a significant amount of evidence that this came from that laboratory in Wuhan,” Pompeo said on ABC’s “This Week.” “These are not the first times that we’ve had a world exposed to viruses as a result of failures in a Chinese lab.”

Pompeo stopped short of saying the virus was man-made, noting that he agreed with a report by the Office of the Director of National Intelligence that ruled out genetic modification or it having been man-made.

The virus’s origin has become a flash point in the pandemic and ratcheted up tensions between the U.S. and China. President Donald Trump has escalated efforts to attach blame to China as U.S. pandemic deaths pass 66,000.

“I’ve seen what the intelligence community has said,” said Pompeo. “I have no reason to believe that they’ve got it wrong.” Pompeo declined to say whether the Chinese intentionally released the virus. “I don’t have anything to say about that,” he said.

Trump and his aides sharpened their criticism of Beijing last week, demanding answers about the virus’s origin. The president tweeted Friday that some U.S. television networks are “Chinese puppets,” while his super-political action committee unleashed anti-China ads.

“China behaved like authoritarian regimes do, attempted to conceal and hide and confuse,” Pompeo said on ABC. “It employed the World Health Organization as a tool to do the same.”

The secretary said China continued to block access by health experts from the WHO, as well as U.S. scientists, from getting access to samples of the virus needed for study.

“This is an ongoing threat, an ongoing pandemic,” Pompeo said. “The Chinese Communist Party continues to block access to the Western world, the world’s best scientists, to figure out exactly what happened.”