In a press conference today, Senator Mark Warner (D-VA) called for stronger regulation of online ads. Sen. Warner appeared with Senator Richard Burr (R-NC) on behalf of the Senate Select Committee on Intelligence, which has been investigating Russian interference in the 2016 elections. Facebook has been cooperating with the committee’s investigation, but has drawn some criticism for not immediately providing ads linked to Russian election interference.

“I was concerned at first that some of these social media platform companies did not take this threat seriously enough,” Sen. Warner told reporters. “I believe they are taking it seriously now.”

Sen. Warner also emphasized that new restrictions are necessary to safeguard online platforms against future interference. Warner has joined with Sen. Amy Klobuchar (D-MN) to propose a bill that would regulate online election ads more heavily, bringing them in line with current restrictions on broadcast and print ads. The bill itself has not yet been introduced to Congress, but Warner restated his commitment at the press conference.

“If you see an ad on a social media site, Americans should know whether the source of that ad was a foreign entity,” Warner said, “and if you see something trending, you should know whether that trending is generated by real individuals or bots or falsely identified accounts.”

The core of the issue is roughly $100,000 in Facebook ads that the company now believes were purchased by agents of the Russian government. It’s a federal crime for foreign powers to participate in U.S. campaigns, so the purchase has uncomfortable implications for Facebook. Facebook announced the finding on September 6, after months of denying any Russian election interference had occurred on the platform.

Facebook agreed to turn over the ads on September 21st, having already provided them to the parallel investigation by special counsel Robert Mueller. The company now believes the ads reached 10 million people, and many of the ads were targeted to swing states like Michigan and Wisconsin. The content typically did not mention a specific candidate, but focused on divisive social issues likely to motivate voters.

There has been significant reporting on the Russian ads, but while they’ve been released to the committee, Sen. Burr said there are no plans to release the ads to the public at large. “We don’t release documents provided to our committee, period,” the Senator told reporters. “It’s not a practice that we’re going to get into. If any of those social media platforms want to do that, we’re fine with them doing it.”

At the same time, Warner indicated there would be more details provided in the coming weeks. “There will be more forensics done by these companies,” Warner said. “I think they’ve got some more work to do, and I’m pleased to say I think they’re out doing that work right now.”

Twitter also provided the Senate committee with evidence of Russian activity on its network, although the evidence was far less comprehensive. The company found more than 200 accounts it believes may have been intended for election interference, although it did not find any evidence of illegal campaign spending.

The committee will have a chance to question tech companies directly on those issues in just a few weeks. Facebook, Google, and Twitter are scheduled to testify before the Senate Select Committee on Intelligence on November 1. The House Intelligence Committee has also scheduled a similar hearing to take place in October.

As the committee’s investigation continues, Facebook is already working to restore its reputation in Washington. The company ran a full page ad in today’s Washington Post detailing its commitment to fighting election interference, covering many of the same points made by Mark Zuckerberg in a blog post in September.

The Senators also said that the investigation had led them to trust the conclusions of the intelligence community assessment, which found that leaked emails from the Clinton campaign were the result of an influence campaign personally ordered by Russian president Vladimir Putin. “There is a general consensus among members and staff that we trust the conclusions of the ICA [intelligence community assessment,” Sen. Burr told reporters.

Both Senators emphasized the ongoing threat posed by Russian interference to elections worldwide, and the implications of the apparently successful campaign in 2016. “The overall theme of Russian involvement in the U.S. elections was to create chaos at every level,” Sen. Burr said, “and the fact that we’re still sitting here nine months later discussing it means they’ve been pretty successful.”