The Russian Foreign Ministry told the US Embassy in Moscow on Wednesday that 10 of its staff must leave the country by May 21, in response to a similar measure from Washington.
The ministry said in a statement that it had summoned the deputy head of the American mission, Bart Gorman, and presented him with a memorandum declaring these figures "undesirable".
The ministry described this decision as a reciprocal response to the "unjustified" expulsion of employees of the Russian Embassy in Washington and the Russian Consulate General in New York.
The ministry pledged to take more measures in the near future, as it announced on April 16, to respond to a recent series of "illegal" US sanctions against Russia.
On Friday, the ministry announced a package of countermeasures to respond to the US sanctions, including the expulsion of 10 US diplomats and the banning of eight current and former high-ranking officials from entering the country.
