U.S. national security adviser O'Brien says China has biggest program to interfere in election

U.S. national security adviser Robert O'Brien said on Friday that China has the largest program among countries seeking to interfere in the U.S. election. "We know the Chinese have taken the most active role," O'Brien told reporters.

"We've made it very clear to the Chinese, to the Russians, to the Iranians and others that haven't been publicly disclosed that anyone ... that attempts to interfere with the American elections will face extraordinary consequences," he said.