SAN FRANCISCO – A web site claiming to represent Russia's Internet Research Agency says it ran a network of fake accounts that attempted to interfere in the midterm elections.

Acting on a tip from the FBI, Facebook announced Monday night that it removed more than 100 accounts – 30 on Facebook, 85 on Instagram – covertly engaging in orchestrated activity in French, English and Russian on the eve of the U.S. elections that it feared was linked to Russian operatives with ties to the Kremlin.

Late Tuesday night, Facebook issued another statement, this one saying a web site purporting to represent the Russian outfit had claimed responsibility for the activity and had published a list of Instagram accounts. Facebook stopped short of definitively connecting the IRA to the activity.

"We had already blocked most of these accounts yesterday, and have now blocked the rest," Nathaniel Gleicher, Facebook's head of cybersecurity policy, said in a statement. "This is a timely reminder that these bad actors won't give up."

With Americans headed to the polls Tuesday, social media companies were on high alert for foreign interference, eager not to see a repeat of the 2016 presidential election when the IRA posed as far-right and left-wing groups on Facebook, Google's YouTube and Twitter to churn out divisive messages on hot-button topics such as race and immigration to influence how people voted.

The Instagram accounts, which were undetected by Facebook for at least a year, ran the gamut, some claiming to support feminists, others African-Americans and LGBT communities, Think Progress reported. Many targeted people interested in celebrities such as Rihanna, Kendrick Lamar and the Kardashians or far-right or left-wing commentators. Pages that talked of "libtards" sidled up to conservatives and supporters of Donald Trump, while pages such as "New Blue Wave" were aimed at Democrats. The most popular account focused on comedian John Oliver and had more than 100,000 followers.

The statement claiming to be from the IRA alleged Russian operatives not only influenced how Americans voted but rigged the outcomes in key races. The group is under indictment by special counsel Robert Mueller.

"The victory of the Democratic party is our top priority in these midterm elections," the statement said. Democrats gained control of the House but Republicans expanded their majority in the Senate on Tuesday night.

The group offered up its picks to win their respective races. That list included some Election Night winners, but also Orrin Hatch, who's retiring from the Senate and whose Utah seat was won by former Massachusetts governor and Republican presidential nominee Mitt Romney, and Jeff Flake, the Arizona Republican who is stepping down at the end of his term.

Security experts warned before Tuesday's midterms that bad actors would attempt to take credit for election interference that did not occur.

"Americans need to strike a careful balance between being wary for election manipulation and being skeptical of unsupported claims of manipulation," former Facebook security chief Alex Stamos said Monday.

Graham Brookie, director of the Atlantic Council's Digital Forensic Research Lab, said statements like the one issued Tuesday night would be a low cost way for the IRA to cast doubt, sow political discord and "give more oxygen to their operations."

"This is significant," he said. "I am confident we will learn more in coming days."

In 2014, the IRA began targeting candidates and issues to heighten political rancor and divisions in the contentious presidential race, according to a February indictment which named 13 Russians with ties to the agency. At least 146 million people on Facebook and Instagram were reached by a combination of ads and posts, according to Facebook.

Last month, the Justice Department said it had uncovered another Russian attempt to meddle in the midterm elections. Elena Alekseevna Khusyaynova, 44, of St. Petersburg, Russia, was charged with playing a key role in Project Lakhta, which had an operating budget of $10 million from January through June, to provide "information warfare against the United States," according to the indictment.

After heavy criticism from lawmakers for failing to detect and purge election interference in 2016, Facebook has made safeguarding elections around the world one of its top priorities.

It has set up an elections "war room" on its campus in Menlo Park, California, where data scientists, engineers and other employees monitor foreign election manipulation, disinformation, voter suppression and other security challenges under a large American flag. It's also hired more people and strengthened automated systems to monitor what's posted on Facebook and it has introduced tighter controls on who can buy political ads.

Last week, Facebook CEO Mark Zuckerberg told investors that his company was getting better at detecting foreign election interference but that "there are going to be things that our systems miss, no matter how well tuned we are."

On Monday, Department of Homeland Security Secretary Kirstjen Nielsen, Attorney General Jeff Sessions, Director of National Intelligence Dan Coats and FBI Director Christopher Wray released a joint statement saying foreign operatives were seeking to influence American voters and might allege they pulled off election interference that did not take place.

"Americans should be aware that foreign actors – and Russia in particular – continue to try to influence public sentiment and voter perceptions through actions intended to sow discord," the statement read. "They can do this by spreading false information about political processes and candidates, lying about their own interference activities, disseminating propaganda on social media, and through other tactics."

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