Twitter announced Thursday it was banning advertisements from Russia-based media outlets RT and Sputnik, in response to US intelligence findings that they sought to spread misinformation during the 2016 presidential election.
The response comes amid increased pressure on Twitter and other internet firms to police their platforms, after a series of disclosures showing how Russia-backed entities sought to sow discord and spread false information to manipulate public opinion ahead of last year's vote.
Moscow threatened retaliatory measures while RT also hit back against Twitter, saying the microblogging site had pitched "a large-sum advertising proposal" to promote its election coverage.
"Twitter has made the policy decision to off-board advertising from all accounts owned by Russia Today (RT) and Sputnik, effective immediately," the San Francisco company said.
"This decision was based on the retrospective work we've been doing around the 2016 US election and the US intelligence community's conclusion that both RT and Sputnik attempted to interfere with the election on behalf of the Russian government."
The decision was made "as part of our ongoing commitment to help protect the integrity of the user experience on Twitter," it said.
Twitter said RT and Sputnik may remain "organic users on our platform, in accordance with the Twitter rules."
Twitter also said it would donate the estimated $1.9 million it received from the two Russian groups since 2011 "to support external research into the use of Twitter in civic engagement and elections, including use of malicious automation and misinformation."
Threat of retaliation
Last month, the company apologised for allowing the use of automated accounts or "bots" that spread disinformation during the campaign.
It identified dozens of accounts that contributed to this effort, including from RT. It noted that RT spent $274,100 on Twitter ads in 2016 to promote its tweets regarding news stories.
Russia slammed Twitter's decision and threatened to retaliate.
"We see this as an aggressive move," Russian Foreign Ministry spokeswoman Maria Zakharova told the RIA Novosti agency.
"This is the result of pressure from the American establishment and intelligence services. Retaliatory measures will of course follow," she said.
RT editor-in-chief Margarita Simonyan made similar remarks, saying Twitter's actions could lead to retaliatory measures against US media.
"I never thought that Twitter is under the control of the US security services -- it seemed like a conspiracy theory," she was quoted as saying on RT's website.
RT also alleged that Twitter had encouraged it to buy advertising in order to expand its reach in the US.
"Twitter representatives pitched to RT a large-sum advertising proposal. It was developed around promoting RT's US election coverage on the microblogging platform. This proposal was eventually declined by RT," it said on its website.
"The main idea pitched by Twitter to RT was 'to take a stand.' The more money RT spent, the bigger the reach to American voters that Twitter would provide," it said.
When asked for its reaction, Sputnik said that it "has never used advertising on Twitter."