WASHINGTON — Facebook announced on Thursday that it was taking down three disinformation networks that it said were linked to Russia’s military and intelligence agencies, and to the Internet Research Agency, which was central to Moscow’s interference in the 2016 presidential election.
None of the networks were large, and they operated almost entirely abroad — from Japan to Belarus. But Facebook said it was acting proactively to dismantle infrastructure Russia could use around the Nov. 3 presidential election, either in an effort to influence the vote or to dispute its outcome by calling into question the fairness of the balloting.
“We haven’t seen these networks directly target the 2020 election,” Nathaniel Gleicher, the head of security policy for Facebook, said in an interview. “But they are linked to actors associated with election interference in the U.S. in the past, including in the ‘DCLeaks’ in 2016.”
He was referring to a website later determined to have been set up by a Russian military intelligence agency, the G.R.U., to make public emails hacked from the Democratic National Committee in 2016.
“We want to be proactive,” said Mr. Gleicher, his latest acknowledgment of the criticism Facebook received for being unaware four years ago of how foreign actors, mostly Russian, were making use of the social network to amplify divisive messages, spread disinformation and even organize protests and counterprotests.
Facebook’s action came only two days after the F.B.I. and the Cybersecurity and Infrastructure Security Agency of the Department of Homeland Security issued a joint warning that the vulnerability of American voting systems may be greatest in the days after the election.
Intelligence officials have expressed concerns that Russian and other actors will have a major opening if mail-in ballots are slow to be counted, or there are charges and countercharges about the handling of mail-in ballots, which President Trump has already said are being used to “rig” the outcome.
During that time after the election, the two agencies said, hackers could amplify “disinformation that includes reports of voter suppression, cyberattacks targeting election infrastructure, voter or ballot fraud and other problems intended to convince the public of the elections’ illegitimacy.”
Facebook’s action on Thursday included the removal of one network that involved 214 Facebook users and related pages that focused primarily on Syria and Ukraine — both places where the Russian military is engaged — that involved fake accounts and fictitious personas. According to Facebook, they drove users to outside websites that posted data related to alleged leaks of “compromising information.”
The network had a limited following in the United States, Mr. Gleicher said, and dealt mostly with a range of political subjects including NATO, the Baltics and Belarus.
Another network drove users to a fake, seemingly independent think tank, and encouraged freelance writers to write for it, in an effort to create an echo chamber of pro-Russian views.
In releasing the data, Facebook is trying to inoculate Americans against what happened four years ago: “hack and leak” operations that ended up dumping emails and other insider documents into news coverage of the campaign. But in the past few weeks, the postelection period has garnered new attention, especially now that Mr. Trump has repeatedly signaled that he believes he could lose the election only if Democrats or poll workers cheat.
The subject came up again when senior intelligence officials held closed-door briefings this week for the House and Senate Intelligence Committees. John Ratcliffe, the director of national intelligence, and William R. Evanina, the senior intelligence official given responsibility for election security briefings, emphasized the dangerous situation the United States will find itself in if there are close votes and uncounted absentee ballots in a number of states. Foreign powers, the two men said, could take advantage of the uncertainty and work to erode public confidence in the vote counting.
In a statement Wednesday, Senator Mark Warner, the Virginia Democrat who is vice chairman of the Senate Intelligence Committee, noted that because of the pandemic and the resulting surge expected in voting by mail, results might not be known on election night.
“The intelligence community warned that, as a result, the period immediately before and after the election could be uniquely volatile,” Mr. Warner said.
Mr. Warner said the public should have faith in state and local officials to ensure all votes are counted, and he criticized Mr. Trump’s efforts to cast doubt on the results.
“The president of the United States should not be aiding and abetting foreign adversaries who are working to sow doubts about the legitimacy of the American election system,” Mr. Warner said.
