Moscow claims that the new measures against the media network’s top editors are part of an “information campaign” ahead of the US presidential election.

Russia vowed retaliation after the US announced sanctions against the state-funded Russian media network RT, threatening that they would “make everyone shudder”.

Washington’s actions against the editor-in-chief of the state broadcaster RT, Margarita Simonyan, and her deputy Elizaveta Brodskaia, are an “information campaign” in the run-up to the US presidential elections in November, the Russian Foreign Ministry said.

“When the authorities resort to such primitive methods to influence their voters, this is the decline of ‘liberal democracies,'” ministry spokeswoman Maria Zakharova said in a statement on Thursday.

“There will be an answer,” Zakharova said.

On Wednesday, two more RT employees, Kostiantyn Kalashnikov and Elena Afanasyeva, were charged by the US with attempting to influence the upcoming election.

They are accused of funneling $10 million to a Tennessee-based company that used social media influence to “create and distribute content to a U.S. audience that contained hidden messages from the Russian government.”

“It is obviously an operation, an information campaign … that has been prepared for a long time and is necessary before the final stage of the electoral cycle,” Zakharova told state news agency Ria Novosti earlier, adding that the reaction would be harsh and “make everyone shudder.”

“We warn that attempts to expel Russian journalists from the territory of the United States, create unacceptable conditions for their work, or otherwise hinder their activities, including through the use of visa instruments, will form the basis for symmetric and/or asymmetric retaliation against the American media,” she said.

Washington says Moscow – which intelligence officials say favors Republican Donald Trump – remains the biggest threat to the election, even as the FBI continues to investigate allegations that Iran hacked the presidential campaigns of the former Republican president and Democrat Kamala Harris.

The US State Department announced that it would take action against several employees of Russian state media outlets, classifying them as “foreign missions” and offering a cash reward for information provided to the US government about foreign election interference.

In addition, the media company Rossiya Segodnya and its subsidiaries RIA Novosti, RT, TV-Novosti, Ruptly and Sputnik will be added to the list of foreign missions. They will then have to register with the US government and disclose their assets and personnel in the US.

Russia’s threat of a harsh response comes at a time when most U.S. media outlets have reduced their staff or withdrawn their personnel from Russia following the launch of their Ukraine offensive, which was accompanied by a massive crackdown on dissidents at home.