Facebook said it has uncovered "sophisticated" efforts, possibly linked to Russia, to influence US politics on its platforms.
The company said it removed 32 accounts from Facebook and Instagram because they were involved in "coordinated" political behaviour and appeared to be fake. Nearly 300,000 people followed at least one of the accounts.
Facebook stopped short of saying the effort was aimed at influencing the US midterm elections in November, although the timing of the suspicious activity would be consistent with such an attempt.
According to a Facebook official, the company this week briefed members of the House and Senate as well as officials at the Department of Homeland Security.
The official declined to be named because the briefings were private. Facebook disclosed its findings after The New York Times reported on them earlier Tuesday.
The company said it doesn't know who is behind the efforts, but said there may be connections to Russia.
Links to Russia Internet Research Agency
Facebook said it has found some links between the accounts it removed and the accounts created by Russia's Internet Research Agency that it removed before and after the 2016 US presidential elections.
The company gave a detailed breakdown of what it had found on its website on a page headlined "Removing Bad Actors on Facebook".
Virginia Senator Mark Warner, the top Democrat on the Senate intelligence committee, called the disclosure "further evidence that the Kremlin continues to exploit platforms like Facebook to sow division and spread disinformation."
The earliest page was created in March 2017. Facebook says more than 290,000 accounts followed at least one of the fake pages. The most followed Facebook pages had names such as "Aztlan Warriors," ''Black Elevation," ''Mindful Being," and "Resisters."
Facebook didn't provide detailed descriptions of those pages. But the names it released are reminiscent of groups set up by Russian agents to draw in and manipulate Americans with particular ethnic, cultural or political identities ahead of the 2016 election. That effort targeted people with both liberal and conservative leanings.
Facebook says the pages ran about 150 ads for $11,000 on Facebook and Instagram, paid for in US and Canadian dollars. The first ad was created in April 2017; the last was created in June 2018.
The company added that the perpetrators have been "more careful to cover their tracks" than in 2016, in part because of steps Facebook has taken to prevent abuse over the past year. For example, they used virtual private networks and internet phone services, and paid third parties to run ads on their behalf. After it became clear that Russia-linked actors used social media to try to influence the 2016 US election, Facebook has stepped up its efforts to ensure that what happened then does not happen again. But the disruptors are stepping up their efforts as well.
"We face determined, well-funded adversaries who will never give up and are constantly changing tactics," Facebook said in a statement.
During a conference call Tuesday, Facebook executives declined to paint a broader nature of the pages, including whether they included a range of political positions. They also did not say whether any of the activity mentioned specific candidates or politicians, and were careful to say that Facebook is not "publicly" linking the activity to any group or government.
California Rep. Adam Schiff, the top Democrat on the House intelligence committee, said more work needs to be done before the midterm elections. "Foreign bad actors are using the exact same playbook they used in 2016," he said. They are "dividing us along political and ideological lines, to the detriment of our cherished democratic system."
President Donald Trump has offered mixed message on Russian interference, at times even calling it a "hoax." After appearing to question whether the Russians would try again to interfere earlier this month, he acknowledged last week in a tweet that the midterms were a likely target. But he said that Democrats, not his fellow Republicans, would be the ones targeted.