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Certain fake social media accounts identified by Facebook and Twitter that were initially geared toward sowing discord before the 2016 U.S. presidential election — frequently targeting then-candidate Hillary Clinton — pivoted after the votes were counted, shifting focus toward undermining the legitimacy of Donald Trump’s victory, lawyers for Facebook and Twitter told the Senate Judiciary Committee Tuesday.

Facebook Vice President and General Counsel Colin Stretch and Twitter Acting General Counsel Sean Edgett acknowledged the shift, responding to a question by Sen. Lindsey Graham, R-South Carolina.

A source at Facebook tells CBS News that Stretch was referring to 470 Russian accounts that the company previously acknowledged had purchased ads prior to the election. After Trump won the election, some of those same accounts began targeting him. The accounts, which were linked to a Russian troll farm called the Internet Research Agency, were later removed by Facebook.

Edgett said during his testimony that Twitter is dedicated “to uncovering what happened in 2016 and by taking steps to prevent it from happening again.” 

In testimony submitted before Stretch’s appearance, Facebook also acknowledge that in the weeks leading up to the 2016 U.S. election, Facebook shut down 5.8 million fake accounts in the United States, and disclosed that as many as 126 million people could have seen posts from the Internet Research Agency over the course of three years. 

Stretch said Facebook takes what happened during the 2016 election very seriously. The company’s own investigation is ongoing, he said, describing the changes the company is making.  

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