Russia said on Thursday it was expelling two US diplomats whom it accused of working with a Russian national charged with collaborating with a foreign state.
The Foreign Ministry said in a statement it had summoned US envoy Lynne Tracy and told her that embassy First Secretary Jeffrey Sillin and Second Secretary David Bernstein must leave Russia within seven days.
"It was also emphasized (to Tracy) that illegal activities of the US diplomatic mission, including interference in the internal affairs of the host country, are unacceptable and will be resolutely suppressed,"Russian Foreign Ministry statement
"The named people conducted illegal activity, maintaining contact with Russian citizen R. Shonov, accused of 'confidential cooperation' with a foreign state," the Russian statement said.
The US State Department said the expulsion of the two diplomats was unprovoked and warned that Washington would respond appropriately.
"This unprovoked expulsion of our diplomatic personnel is wholly without merit, as is the case against a former Russian contractor of our embassy," State Department spokesperson Matthew Miller told reporters.
"Yet again, Russia has chosen confrontation and escalation over constructive diplomatic engagement. It continues to harass employees of our embassy, just as it continues to intimidate its own citizens. We regret that Russia has taken this path and you can certainly expect that we will respond appropriately to their actions."
Robert Shonov was employed by the US Consulate General in the eastern Russian city of Vladivostok for more than 25 years until Russia in 2021 ordered the dismissal of the US mission's local staff.
Russia's FSB security service published a video in August showing a purported confession by Shonov in which he said Sillin and Bernstein had asked him to collect information about Russia's war effort in Ukraine, its annexation of "new territories," its military mobilization and the 2024 presidential election.
In the video, Shonov said he was told to gather "negative" information on these topics, to look for signs of popular protest and to reflect these in his reports.
Washington accused Moscow of attempting to intimidate and harass US employees after Russian state media reported the charges against Shonov and said the FSB planned to question embassy employees who had been in touch with him.
When he was arrested in May, the State Department said the case highlighted Russia's "blatant use of increasingly repressive laws" against its own citizens. It said the allegations against Shonov were "wholly without merit."
In its statement, the Russian Foreign Ministry said Shonov had been paid to complete tasks aimed at damaging Russia's national security.
"It was also emphasized (to Tracy) that illegal activities of the US diplomatic mission, including interference in the internal affairs of the host country, are unacceptable and will be resolutely suppressed," it said.
"The Russian side expects Washington to draw the right conclusions and refrain from confrontational steps."
Relations between Moscow and Washington have plunged to their worst point for more than 60 years because of the war in Ukraine. The US is providing advanced weaponry to Ukraine and has hit Russia with sanctions in response to its invasion in February 2022.