Top officials from Facebook, Google, and Twitter told a congressional panel Tuesday that their platforms hosted a disinformation campaign carried out over their networks by Russian state actors. The propaganda centered on the presidential election, immigration, gun rights, gay rights, and racial issues, the companies said. None of the three organizations said they supported proposed legislation requiring them to disclose who is buying political advertisements on their platforms, although these Web companies promised more public transparency about who is buying ads on their networks.

The hearing before the Senate Judiciary Committee comes as Facebook conceded that as many as 126 million people were exposed to Russian operations on its site during the 2016 presidential election. Facebook said a "troll farm" tied to the Kremlin, called the Internet Research Agency, posted 80,000 times between 2015 and 2017, which resulted in 29 million direct appearances on Facebook news feeds. Thanks to real users liking, sharing, and commenting on these posts, the campaign scored between 87 and 126 million impressions, according to Facebook.

The campaign had real-world consequences. To sow discord, the propaganda sparked a New York street protest over President Donald Trump's victory—prompting between 5,000 to 10,000 protesters to convene on Manhattan's Union Square on November 12.

Sen. Lindsey Graham (R-S.C.) said the tech sector needs to weed out bad speech and "keep the good."

"This is a national security challenge of the 21st Century," he said.

Sen. John Kennedy (R-La.) told the leaders of Facebook, Google, and Twitter that "your power sometimes scares me." Later in the hearing, he added: "I do find your power breathtaking."

Sen. Dianne Feinstein (D-Calif.) said the disinformation campaign underscores the "frightening power of social media." She said the Russians "easily and successfully" turned "modern technologies to their advantage."

Colin Stretch, Facebook's general counsel, said (PDF) foreign actors had "abused" the social networking site.

I want to be clear: the foreign interference we saw is reprehensible and outrageous and opened a new battleground for our company, our industry, and our society. That foreign actors, hiding behind fake accounts, abused our platform and other Internet services to try to sow division and discord—and to try to undermine our election process—is an assault on democracy, and it violates all of our values.

Stretch said that, when it came to election propaganda, the disinformation attacked Democratic candidate Hillary Clinton before the election and targeted Donald Trump after he won the election.

"The activity, again, really appears to address a wide range of hot-button topics and appears directed at fomenting discord," Stretch told lawmakers. About an hour later, he described the Russian campaign as a "sophisticated and systemic effort to interfere in the election."

For its part, Google said that a Russian disinformation campaign on YouTube amounted to 1,108 videos, which totaled 43 hours of content. They were published by 18 channels "likely associated" with the Internet Research Agency, Google said.

As Ars noted Monday, those YouTube videos were posted in English with "content that appeared to be political" sandwiched between non-political content like travelogues. The channels in question racked up 309,000 views between June 2016 and November 2016. Google did not disclose YouTube channel or account names associated with this content.

"The videos were not targeted to any particular segment of the US population as that is not a feature available on YouTube, but we did observe that links to those videos were frequently posted to other social media platforms," Richard Salgado, Google's senior counsel, told lawmakers,

According to Twitter, Russian media outlet Russia Today (RT) is estimated to have paid $1.9 million for global advertising to Twitter since it began advertising through the service, including $274,100 in US-targeted advertising in 2016. Days ago, Twitter announced it would block paid advertisement posts by Russian media outlets RT and Sputnik. To illustrate how easily the propaganda could spread, even Twitter CEO Jack Dorsey unknowingly retweeted tweets from the Internet Research Agency.

Sean Edgett, Twitter's general counsel, said the company was "committed" to preventing this from happening again. "We are committed to working every single day at solving this problem." He later added, "our tools are getting better every day." Representatives from Google and Facebook made the same promises.

But, again, none of these tech giants would state on the record that their companies supported bipartisan legislation requiring them to disclose who is buying political advertisements on their platforms and maintain records of those ad buys.

"Will you support our bill?" Sen. Amy Klobuchar (D-Minn.) asked the three representatives.

"We stand ready to work with you and your co-sponsors on that legislation going forward," Facebook's Stretch replied.

"The same goes for Twitter," Edgett added.

Google's Salgado said, "We certainly support the goals of the legislation."

Sen. Al Franken, a Democrat of Minnesota, noted that some of the Russian-backed campaign ads bought on Facebook were paid for in Russian rubles.

"How could you not connect those two dots?" Franken asked Facebook's Stretch.

"In hindsight," Stretch replied, "it's one we missed."