When you think about it, using social media as a means of pushing a particular narrative by a hostile foreign government really isn’t that difficult.

According to a new report from the Daily Beast, Russian propagandists attempted to organize pro-Trump rallies in at least 17 U.S. cities, using Facebook pages.

The demonstrations—at least one of which was promoted online by local pro-Trump activists— brought dozens of supporters together in real life. They appear to be the first case of Russian provocateurs successfully mobilizing Americans over Facebook in direct support of Donald Trump.

The Aug. 20, 2016, events were collectively called “Florida Goes Trump!” and they were billed as a “patriotic state-wide flash mob,” unfolding simultaneously in 17 different cities and towns in the battleground state. It’s difficult to determine how many of those locations actually witnessed any turnout, in part because Facebook’s recent deletion of hundreds of Russian accounts hid much of the evidence. But videos and photos from two of the locations—Fort Lauderdale and Coral Springs—were reposted to a Facebook page run by the local Trump campaign chair, where they remain to this day.

“On August 20, we want to gather patriots on the streets of Floridian towns and cities and march to unite America and support Donald Trump!” read the Facebook event page for the demonstrations. “Our flash mob will occur in several places at the same time; more details about locations will be added later. Go Donald!”

The Facebook page that organized the events was called Being Patriotic, and had over 200,000 members. There was also a related Twitter account called @March_for_Trump.

Huge, enthusiastic crowd greeted the Trump RV at Wings Plus in Coral Springs Fl pic.twitter.com/UaGAFS0XU1

— Dolly Trevino Rump (@dollytrump) September 1, 2016

Both accounts have been deleted, at this point. Facebook did a purge of any accounts they determined to be “fake,” or related to Russian players and seem to have deleted the page, as of August 27.

Events promoted by the page last year included a July “Down With Hillary!” protest outside Clinton’s New York campaign headquarters, a September 11 pro-Trump demonstration in Manhattan, simultaneous “Miners for Trump” demonstrations in Philadelphia and Pittsburgh in October, and a pro-Trump rally outside Trump Tower last November, after his election victory.

Facebook admitted earlier this month that they’d determined there were around 3,000 ads, coming from 470 accounts that were linked to what they’re calling “Russian troll farms.”

The pro-Trump events represent “the next level” of suspected Russian influence operations, said Clint Watts, a former FBI agent who has testified about those operations to a Senate committee investigating them.

“This would be a direct effort that they attempted that’s more than online promotion,” Watts told The Daily Beast. “‘Let’s organize and try to get people to move to events in a proactive way around a candidate. Again, if it traces back to Russia, you can’t deny that’s foreign influence in an election.”

And clearly, they had a favorite and an agenda.

The thing about Facebook event pages is that anyone can mark themselves as attending. That doesn’t mean they’ll show up, so it’s hard to determine how much of an impact the pages had.

Special counsel Robert Mueller, as well as congressional investigators have been shown the ads, and they may seek to have Facebook executives testify about their origins.