Facebook has identified and banned hundreds of accounts, groups and pages engaged in misleading political behaviour, a far larger discovery than a 'sophisticated' effort it reported three weeks ago with great fanfare.
The social network said that it had removed 652 pages, groups, and accounts linked to Russia and, unexpectedly, Iran, for "coordinated inauthentic behavior" that included the sharing of political material.
Facebook has significantly stepped up policing of its platform since last year, when it acknowledged that Russian agents successfully ran political influence operations on its platform that were aimed at swaying the 2016 presidential election.
Other social media networks have done likewise, and continue to turn up fresh evidence of political disinformation campaigns.
Facebook's action in late July against 32 accounts possibly linked to Russia generally involved U.S political activity ahead of the midterm elections in November. By contrast, the latest group of apparently fake accounts appeared more intent on influencing U.S foreign policy and regional politics in the Middle East.
Shortly after Facebook's announcement, Twitter revealed that it had also suspended 284 accounts for "coordinated manipulation," many of them apparently originating from Iran.
A day earlier, Microsoft also reported a new Russian effort to impersonate conservative U.S websites, potentially as part of an espionage campaign.
The social network said it had not concluded its review of the material and declined to say how or why the state-backed actors were behaving the way they did. But it said it has informed the U.S and U.K governments as well as the U.S Treasury and State departments because of ongoing sanctions against Iran.
"There's a lot we don't know yet," CEO Mark Zuckerberg said on a hastily called conference call with reporters.
"You're going to see people try to abuse the services in every way possible ... including now nation states," he said.
He described the deception campaigns as "sophisticated and well-funded efforts that aren't going to stop."