President Vladimir Putin has said the United States will have to cut its diplomatic staff in Russia by 755 under new sanctions from Moscow.
On Friday, Russian's foreign ministry ordered a reduction by September 1 in the number of US diplomats in Russia.
It said it was ordering the US embassy to reduce the number of embassy and consular employees in the country to 455 in response to the US Senate's approval of a new package of sanctions.
It was not clear then how many reassignments that would mean from the Moscow embassy and the three US consulates in Russia.
Mr Putin said in an interview shown on state television on Sunday that he ordered the move because he "thought it was the time to show that we're not going to leave that without an answer".