The FBI monitored social media on Election Day last year in an effort to track a suspected Russian disinformation campaign utilizing “fake news,” CNN has learned.

In the months leading up to Election Day, Twitter and Facebook were the feeding grounds for viral “news” stories floating conspiracies and hoaxes, many aimed at spreading negative false claims about Hillary Clinton.

On Election Day, dozens of agents and analysts huddled at a command center arrayed with large monitoring screens at the FBI headquarters in Washington watching for security threats, according to multiple sources.

The agencies under Obama’s control “had identified social media user accounts behind stories, some based overseas, and the suspicion was that at least some were part of a Russian disinformation campaign,” according to CNN.

“We were right on the edge of Constitutional legality,” a person briefed on the investigation told the network. “We were monitoring news.”

The FBI and the other agencies apparently weren’t concerned about so-called “fake news” being circulated about Trump.

CNN, nor its anonymous sources, indicated which stories the Obama administration deemed to be “fake news.”