The top Democrat on the Senate Intelligence Committee berated lawyers for social media giants Facebook Inc., Twitter Inc. and Google for a lethargic response to Russian interference in U.S. politics, as the companies’ lawyers faced a second day of grilling in Congress.

“Your first presentations were less than sufficient,” Mark Warner said at the panel’s hearing Wednesday, saying lawmakers were at first “blown off” by companies that in effect said, “Nothing like this happened. Nothing to see here.”

Facebook’s General Counsel Colin Stretch was dressed down when he was unable to tell Warner whether his company had cross-checked 30,000 fake accounts it took down before the French election to see if any had been active in the U.S.

“I will have to come back to you on that, sir,” Stretch said.

“We’ve had this hearing scheduled for months,” Warner of Virginia replied. “I find your answer very, very disappointing."

It was a rocky start to what was likely to be a very long day for the companies before the Senate and House Intelligence committees as members led by Warner push for legislation that would require the companies to disclose the source of campaign ads. If anything, the questioning of the companies -- which cultivate their influence in Washington through lobbying and campaign contributions -- was even more pointed than at a Senate Judiciary subcommittee session Tuesday.

The Intelligence Committee focused not just on Russian-backed advertising but to the extent to which unpaid posts and articles were used in an effort to manipulate American opinion and create division.

Instagram Manipulated

In the latest disclosure of manipulation of the social networks, Stretch testified Wednesday that 120,000 Russian-linked posts on its Instagram application reached 16 million people starting in October 2016 and about 4 million before that. Facebook has said previously that about 170 Instagram accounts had been deleted.

While Republican Senator Richard Burr, the committee’s chairman, joined in chiding the social-media companies for failing to do more, he resisted Democratic assertions that Russian-linked ads may have been targeted to key states to help Donald Trump win the presidency.

“What you haven’t heard is almost five times more ads were directed at the state of Maryland,” a state that wasn’t in play in the election, than in Wisconsin, which was a key state in Trump’s victory, Burr said. He said only $300 was spent in Pennsylvania, a battleground state.

Tip of Iceberg

Warner said that paid Russian ads on social-media networks are only a small part of a campaign to manipulate U.S. opinion and undermine democracy through viral postings.

“These ads are just the tip of a very large iceberg,” he said. “The real story is the amount of misinformation and divisive content that was pushed for free on Russian-backed pages, which then spread widely on the news feeds of tens of millions of Americans.”

Senator Dianne Feinstein of California, noting that she represents Silicon Valley, told the witnesses, “I must say I don’t think you get it” and that their “vague answers” aren’t sufficient. She said, “what we’re talking about is a cataclysmic change. What we’re talking about is cyberwarfare.”

At the hearing of a Senate Judiciary subcommittee on Tuesday, attorneys for the companies were forced to acknowledge that they aren’t sure they’ve measured the full extent of foreign manipulation of their social networks and don’t yet have the technology to ensure it won’t happen again.

“We need to understand the behavior and we need to have the capacity both as a company and as an industry to be able to track it and eradicate it,” Stretch, the Facebook general counsel. He said the company will double its safety and security staff to 20,000, including contract workers, by the end of 2018 to help track foreign interference and extremist postings.

The companies stopped short of endorsing proposed legislation that would require them to disclose all purchasers of political advertising, as old-line broadcasters have long been required to do. While some Republicans said such requirements would raise constitutional questions, Democrats on the panel said Congress must act.

Warner is a prime advocate of legislation to impose new disclosure requirements on social media, while Burr of North Carolina has said he would wait to decide until after Wednesday’s hearing.

The companies drew ridicule Tuesday from Democratic Senator Al Franken, who expressed amazement that Facebook had failed to detect that Russians were behind American political ads on its platform even though some of them were paid for in rubles.

“People are buying ads on your platforms with rubles! They’re political ads,” the senator from Minnesota said. “You can’t put together rubles with a political ad and go like, ‘Hmmm, those two data points spell out something bad?’”

“It’s a signal we should have been alert to and in hindsight, it’s one we missed,” said Facebook’s Stretch.

The scope of Russian interference through paid ads was drawn in prepared testimony to the Judiciary subcommittee Tuesday by Stretch. He said that 29 million people on the platform were directly served content from accounts backed by the Internet Research Agency, a pro-Kremlin Russian group.

After those posts were liked, shared and commented on via Facebook’s social network, they landed in the News Feeds of about 126 million people at some point over a two-year period, the testimony shows. That’s equivalent to about 40 percent of the U.S. population.