Federal investigators are examining whether far-right news sites played any role last year in a Russian cyber operation that dramatically widened the reach of news stories — some fictional — that favored Donald Trump’s presidential bid, according to a new report.

The Hill reported the probe is focused on discovering whether Russian operatives used conservative outlets to help spread stories favoring now-President Trump, McClatchy said Monday after confirming with two people familiar with the inquiry that the FBI’s Counterintelligence Division is driving the investigation.

The sources said Russian operatives seemingly strategically timed computer commands called “bots” to blitz social media with pro-Trump stories. Many of the stories were simply fake news meant only to deceive people into having a better opinion of Trump and a worse opinion of Clinton, his opponent. Some of the stories were a mixture of fake and real news, but again they had the purpose of deceiving people into liking Trump.

These media blitzes were set to go out whenever Trump started struggling in the polls against Clinton.

McClatchy’s sources said the bots mainly created millions of Facebook and Twitter posts linking to articles on far-right websites including Breitbart News, InfoWars and the Kremlin-backed RT News and Sputnik News.

Federal investigators are now examining whether the far-right news organizations took any actions aiding Russian operatives. The bots could have amplified pro-Trump news on Facebook and Twitter without the knowledge of the media outlets.

“This may be one of the most impactful information operations in the history of intelligence,” one former U.S. intelligence official told McClatchy, speaking on the condition of anonymity due to the matter’s sensitivity.

FBI Director James Comey earlier Monday confirmed the Department of Justice (DOJ) is scrutinizing Russia’s meddling in the 2016 race, including any possible ties between Moscow and officials from Trump’s election campaign.

“As you know our practice is not to confirm the existence of an ongoing investigation,” he said during a House Intelligence Committee hearing.

“But in unusual circumstances where it is in the public interest, it may be appropriate to do so,” Comey added, noting the DOJ had authorized him to break bureau policy and publicly disclose the probe.

“This is one of those circumstances. I can promise you we will follow the facts wherever they lead.”

Comey said the FBI investigation started in July 2016, long before the election.