(Loic Venance/AFP/Getty Images)

Twitter is planning to notify users who may have been exposed to Russian propaganda during the 2016 presidential election, the company's head of public policy told a Senate panel Wednesday.

The initiative follows Facebook's move, announced last year, to create an online tool for people to learn whether they liked or followed Facebook and Instagram accounts generated by a Russian troll farm known as the Internet Research Agency (IRA). Twitter's bid is the latest example of a major social-media company grappling with the fallout of foreign election meddling, attempting to repair its reputation after lawmakers heavily criticized Silicon Valley for allowing its platforms to be widely exploited.

“We will be working to identify and inform individually the users who may have been exposed to the IRA accounts during the election,” Twitter's Carlos Monje Jr. said. Twitter declined to comment beyond Monje's remarks.

In the fall, top officials from Twitter, Facebook and Google appeared before multiple congressional committees to answer pointed questions about their role in facilitating election interference. The hearings revealed for the first time the full scope of Russian disinformation campaigns and offered the public the first glimpse of online ads wielded by foreign operatives to sow disinformation and discord among the U.S.  public. Lawmakers from both parties scolded the companies for failing to better identify, defuse and investigate Russia's campaign to manipulate U.S. voters.

Unlike Twitter and Facebook, Google has said in a written response that notifying users who were potentially misled by Russian disinformation would be too challenging, according to Sen. Richard Blumenthal (D-Conn.), who had previously asked the companies about notifying their users. “I am disappointed by Google’s written response,” he said during the hearing. “It essentially blew off my concerns by saying the nature of the platform made it difficult to know who has viewed its content.”

Google did not immediately respond to a request for comment.

While Wednesday's hearing in the Senate Commerce Committee was ostensibly about how social-media companies can better combat terrorism, it veered onto other topics, primarily Russia. Sen. Bill Nelson (D-Fla.), for instance, during his initial round of questioning, asked an expert witness to explain how foreign agents might meddle in the upcoming midterms.

“There has been no response from the U.S. government with regards to Russian influence campaigns on social media, and so therefore they have stayed on course with their operations,” said Clint Watts, a fellow at the Foreign Policy Research Institute. “They realize that this playbook works very well, is extremely cost-effective, and there’s been almost no downside at least at this point of doing it.”

Democratic Sens. Tammy Baldwin (Wis.) and Tom Udall (N.M.) also raised the issue of domestic terrorism, specifically the rise of white nationalists and white supremacists. Representatives from Google, Facebook and Twitter said their policies that ban the incitement or glorification of violence apply to all extremist groups, regardless of ideology. Watts, of the Foreign Policy Research Institute, said it's challenging for social-media companies to police the speech of white hate groups because the federal government does not provide clear definitions on what a domestic extremist group is.

Responding to intensifying pressure in Europe, Facebook confirmed Wednesday that it is opening a new probe into Russian interference in Britain’s 2016 referendum to exit the European Union.