Russia has told the US government to limit the staff it has in the country in response to increased sanctions.
Earlier this week, the US Senate made an almost unanimous vote to increase the measures on Russia, despite opposition by the Trump administration.
In response, the Russian Government has reportedly suspended the US embassy's ability to use diplomatic properties in Moscow.
It has also told its American counterpart it must reduce the number of staff present in Russia, which is believed to number around 1,100 diplomats.
Russia says the bill - which was passed by both sides of the house - showed the relationship with Russia had "fallen hostage" to domestic struggles in US politics.
The deadline for this staff reduction has been listed as September 1 in a statement by the Russian Foreign Ministry.