Speaking alongside his British counterpart in London, FBI Director Christopher Wray issued his starkest warning yet about the national security threat to the West from China, even as intelligence officials in Washington released a report about Beijing’s efforts to influence state and local politics in the U.S.

In a first-ever joint appearance Wednesday with the director of Britain’s MI5, the U.K.’s domestic intelligence agency, Wray raised the possibility that China might be inching closer to invading Taiwan, noting that Beijing has been taking steps to shield its economy from sanctions that would come after such a move.

“In our world, we call that kind of behavior a clue,” he said, adding that were an invasion to happen, “it would represent one of the most horrific business disruptions the world has ever seen.”

The Chinese Embassy in Washington did not respond to a request for comment. The Chinese Foreign Ministry said Wednesday, "In order to mislead the public, the U.S. has worked hand in glove with NATO to hype up competition with China and stoke group confrontation.”