"We've removed hundreds of pages and accounts involved in coordinated inauthentic behaviour - meaning they misled others about who they were and what they were doing", Ms Sandberg told the Senate Intelligence Committee.
Facing growing criticism from President Trump and GOP lawmakers that social media platforms favor liberals, Dorsey insisted Twitter is impartial. That scrutiny has led to additional criticism over the companies' respect for user privacy and whether conservatives are being censored.
"Each of you have come a long way with respect to recognizing the threat", Senator Mark Warner, the committee's top-ranking Democrat, said.
"Clearly, this problem is not going away", Burr said.
"I'm disappointed Google decided against sending the right senior level executive", Sen.
"The bad news, I'm afraid, is that there is a lot of work still to do".
As reported by CoinDesk and other outlets, Twitter has been ground-zero for identity scams that seek to defraud users out of their cryptocurrency holdings.
The start of the Senate hearing saw the sort of person the social media giants contend with in the form of Mr Alex Jones, the conspiracy theorist with a considerable following, whose radio show has recently been taken off platforms like YouTube and Facebook.
"There is no evidence that the algorithms of social networks or search results are biased against conservatives".
Social media experts say trust is the cornerstone of their business and they must continue to evaluate the safety and security of their platforms.
Appearing before the House Energy and Commerce Committee Wednesday, Dorsey said the offending tweet was up for "five hours", although Domenech tweeted Saturday that the image had been up for "half a day" and he had to "raise a ruckus" before it was deleted.
The Senate hearing focused primarily on the use of social media by Russian Federation and other foreign actors in the 2016 election, with executives promising to do more to combat such meddling in the future. "My point of the first question was, does that fit your political views [which] your company is following, because there seems to be a pattern here".
"We believe that we have a responsibility to prevent the misuse of our platforms and we take that very seriously", said Walker, who has previously testified before the committee and was the official Google hoped to send again.