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Twitter is banning two Kremlin-backed news outlets, Russia Today and Sputnik, from advertising on its platform, the company said in a blog post on Thursday.

The decision is perhaps Twitter's most aggressive move yet and comes one week before representatives from Twitter, Google, and Facebook are set to testify before Congress about the role their platforms played in Russian interference in last year's election.

"We did not come to this decision lightly, and are taking this step now as part of our ongoing commitment to help protect the integrity of the user experience on Twitter,” the blog post said.

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Related: Twitter Launches Ad Transparency Center in Wake of Russia Probe

Twitter's public policy team said it made the decision "based on the retrospective work we've been doing around the 2016 U.S. election." The company also cited a report from the U.S. intelligence community that named RT and Sputnik as contributors to the "influence campaign by serving as a platform for Kremlin messaging to Russian and international audiences."

"Retaliatory measures will naturally follow," a Russian Foreign Ministry spokeswoman told RT on Thursday, adding that the "aggressive" step appeared to be "the result of pressure from some of the U.S. establishment and security services."

Twitter said the decision related to investigations regarding last year's election. Leon Neal / AFP - Getty Images

While RT and Sputnik are banned immediately from advertising, they will be able to continue to keep their Twitter accounts as long as they continue to follow Twitter's rules.

Twitter said it has earned $1.9 million from RT since the outlet became an advertiser in 2011. That includes the $274,100 RT spent on Twitter advertisements last year, including promoting tweets "that definitely or potentially targeted the U.S. market," Twitter confirmed last month.

That money will be donated to support third-party organizations studying the role Twitter plays in civic engagement.

Twitter also announced a new arm this week called the Advertising Transparency Center, which will provide Twitter users with more information about the advertisements they're seeing, why they're seeing them, and tools to provide feedback.

Twitter's move to self-regulate comes as lawmakers are considering legislation that, if passed, would require social media companies to maintain public records for election ads run on their platforms, holding them to the same disclaimers seen in broadcast and print election ads.