President Vladimir Putin has said 755 US diplomats must leave Russia, in response to new sanctions against his country.
The Russian leader said the officials would be expelled by September 1.
The move makes good on a threat issued on Friday to reduce the number of US diplomats in Russia after Congress passed a package of new financial sanctions with overwhelming support.
Mr Putin and oligarchs close to him are all targeted by the sanctions.
Donald Trump is yet to sign the sanctions into law, but the White House said he "intends" to do so.
Speaking in a television interview, Mr Putin said Russia’s patience in waiting for improved relations with the United States had worn out.
“We waited for quite some time that maybe something will change for the better, had such hope that the situation will somehow change, but, judging by everything, if it changes, it will not be soon,” Mr. Putin said.
He added that he did not expect any improvement in US-Russia ties any time soon.
The Senate passed the new sanctions 98-2, two days after the House of Representatives pushed the measure through by 419-3.
A caveat within the sanctions preventing Mr Trump from scaling back or waiving them without Congress's permission was also passed.
The legislation is aimed at punishing Moscow for interfering in the 2016 presidential election, something Mr Trump has repeatedly cast doubt over.
The president has blasted investigations into the extent of Russia's interference and whether the Trump campaign colluded with Moscow as a "witch hunt".
In December 2016, former President Barack Obama ordered the expulsion of 35 Russian diplomats from the United States as punishment for Russia’s alleged election interference.
At the time Mr Putin chose not to retaliate, a move Mr Trump described as "very smart".