Fake news and social media posts are such a threat to U.S. security that the Defense Department is launching a project to repel "large-scale, automated disinformation attacks," as the top Republican in Congress blocks efforts to protect the integrity of elections.

The Defense Advanced Research Projects Agency wants custom software that can unearth fakes hidden among more than 500,000 stories, photos, video and audio clips. If successful, the system after four years of trials may expand to detect malicious intent and prevent viral fake news from polarizing society.

"A decade ago, today's state-of-the-art would have registered as sci-fi — that's how fast the improvements have come," said Andrew Grotto at the Center for International Security at Stanford University. "There is no reason to think the pace of innovation will slow any time soon.