The Senate Judiciary Committee's Tuesdayfrom Facebook, Twitter and Google delved into details regarding how much the companies knew about Russian interference in the 2016 U.S. election on their platforms -- and what they are trying to do to prevent it from happening in the future.
Colin Stretch, Facebook's general counsel; Sean Edgett, Twitter's acting general counsel; and Richard Salgado, director of law enforcement and information security for Google, answered many questions from committee members and also prompted new questions.
Twitter and Facebook have suspended hundreds of accounts believed to be connected with Russian election-focused activity intended to influence public opinion. On Wednesday, the Senate Intelligence Committee will hold its own hearing on social media influence in the 2016 election.
The Senate Intelligence Committee, Senate Judiciary Committee and House Intelligence Committee are all probing various aspects of Russian meddling in the 2016 election cycle.
Here are the five top takeaways from Tuesday's testimony.
1. Fake accounts attempted to delegitimize Trump's election win
Representatives from Facebook and Twitter said the fake accounts that were eventually taken down tried to delegitimize Donald Trump's victory in the presidential election.
Stretch claimed -- and Edgett agreed -- that the accounts pivoted after the election, shifting their focus from pushing divisive, hot-button issues to questioning Mr. Trump's presidency. A source at Facebook told CBS News, as CBS News', that Stretch was referring to the 470 accounts the company previously acknowledged had purchased ads before the election. The accounts were believed to be linked to a Russian troll farm called the Internet Research Agency. Facebook later removed them.
That development could interest Republicans in pursuing the issue more vigorously.
2. Facebook has 150 staffers devoted to probing terror threats
The social media giant, Stretch revealed, has 150 people devoted to identifying and handling suspected terror-related activity. The company has "thousands" devoted to examining content, and 150 people whose specific job focuses on vetting content for terrorist-related chatter, he said.
3. Concern about other actors
The witnesses were asked whether they believe governments other than Russia operated or are operating fake accounts to influence U.S. elections or policy. Asked whether they believed China, North Korea or any other government wielded such social media weapons, they said they did not believe so.
But Stretch said Facebook is concerned about foreign actors beyond Russia.
"We worry about nation-state actors really from around the globe," Stretch said.
4. Russia's influence on 2016 election outcome difficult to determine
Sen. Mazie Keiko Hirono, D-Hawaii, asked the witnesses if they could say whether or not Russian propaganda and influence had an impact on the election's outcome.
"Senator, we're not well positioned to judge why any one person or an entire electorate voted as it did," Stretch said.
The social media companies emphasized that the number of fake accounts -- though a serious concern -- were few compared to their overall users. But in the end, their influence is difficult, if not impossible, to quantify.
5. Senators aren't satisfied
If there was anything that emerged clearly from Tuesday's hearing, it was how dissatisfied the committee members are with the social media companies' response to foreign influence in U.S. politics.
Sen. Ted Cruz, R-Texas, voiced serious concerns about censoring conservative political views in the process of censoring or deactivating social media accounts.
Sen. John Neely Kennedy, R-Louisiana, said the power of the social media companies to view Americans' activity "scares me."
Sen. Dianne Feinstein, D-California, said she found it "frightening" how easy it was for Russians to launch election interference attempts.
Sen. Chris Coons, D-Delaware, asked why it has taken Facebook so long to come forward and lay out the scope of the problem.
"Why has it taken Facebook 11 months to come forward and help us understand the scope of this problem?" he demanded.
In other words, members still have some unanswered questions and unaddressed concerns about how the tech giants are managing this problem.