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Referring to such companies, which include Facebook Inc and Twitter Inc, Trump told the conservative news outlet in an interview conducted on Tuesday that "I think they already have" interfered in the November 6 election.
"That's on us", she wrote. "That's on us. This interference was completely unacceptable". Still, Sandberg says the company's overall understanding of the Russian activity in 2016 is limited "because we do not have access to the information or investigative tools" that the USA government has.
Twitter CEO Jack Dorsey poses during a photo shoot in Sydney, New South Wales.
The company is getting better at finding and removing "inauthentic" content and now has more than 20,000 people working on safety and security, she said.
"This is an arms race, and that means we need to be ever more vigilant", Sandberg wrote. And Facebook's CEO, Mark Zuckerberg, ran the gauntlet of the House and Senate in April, following the revelations of the Cambridge Analytica data harvesting operation.More news: Al Sharpton takes shot at Trump at Aretha Franklin's funeral
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Per Business Insider, Google Senior Vice President, Global Affairs and Chief Legal Officer Kent Walker sent written testimony that did not address the absence. "Congress is going to have to take action here".
A spokesperson for Twitter declined to comment, but in past hearings Twitter officials have affirmed the gravity of the situation.
He said Twitter is committed to rooting out abusive activity and "hostile foreign influence". "We are learning from what happened, and we are improving".
Earlier this year the company said it was taking aggressive measures to combat inauthentic accounts.
Dorsey will appear before the US House of Representatives' Energy and Commerce Committee after Republicans raised concerns about how the social media platform polices content. Twitter has been accused by some of suppressing conservative voices on the platform - which the company denied in July.
To kick off his opening statement, Dorsey picked up his phone and said he would be tweeting out his prepared testimony.
"We believe strongly in being impartial, and we strive to enforce our rules impartially", Dorsey will tell lawmakers Wednesday, according to a copy of his prepared remarks released in advance.