The U.S. State Department called Russian President Vladimir Putin's demand that U.S. diplomatic staff in Russia be slashed by 755 personnel "regrettable and uncalled for act" and said Washington was considering a possible response.
"We are assessing the impact of such a limitation and how we will respond to it," a State Department statement said on July 30.
Putin's demand that the United States slash its staff in Moscow came amid an escalating row over new sanctions being planned by the U.S. Congress against Russia.
Speaking in an interview with Russian state television broadcast July 30, Putin said that more than a thousand U.S. diplomats and "support staff" are currently working in Russia, and that "755 must stop their activities."
Moscow ordered the reduction in U.S. diplomatic staff after U.S. lawmakers passed a bill that would impose additional sanctions on Russia and sent it to President Donald Trump for his signature.
The Russian response escalates tensions in the relationship between Washington and Moscow, which has been badly damaged by Russia's aggression in Ukraine, its role in the war in Syria, and its alleged interference in the U.S. presidential election in 2016.
Russia, meanwhile, has stepped up its accusations that Washington is trying to unjustly and "illegally" isolate it with sanctions and other measures.
The Russian Foreign Ministry said the U.S. sanctions legislation confirmed what it called the "extreme aggression" of the United States in international affairs.
Putin's announcement came two days after the White House said Trump would sign the bill, which would require him to seek congressional approval in order to ease sanctions against Moscow.
U.S. Vice President Mike Pence told Fox News in a July 30 interview in Estonia, where he was on an official visit, that Trump had made it "very clear that very soon he will sign the sanctions."
"But at the same time, as we make our intentions clear, we expect Russian behavior to change," Pence said.
The Russian Foreign Ministry had previously said that Washington must reduce its diplomatic staff to 455 people by September 1.
The ministry said that is the number of Russian diplomats in the United States after Trump's predecessor, Barack Obama, expelled 35 Russian diplomats in December -- a response to alleged Russian meddling in the 2016 presidential election and ill-treatment of U.S. diplomats in Russia.
Initial news alerts -- including from Russia's state-run TASS news agency -- on July 30 said that Putin had ordered 755 U.S. diplomats to leave the country, though it later became clear he was talking about overall staff reductions at U.S. diplomatic facilities. Not all of the individuals ordered to cease their work would be U.S. citizens kicked out of the country.
It was not immediately clear how many reassignments the forced drawdown would entail at the U.S. Embassy in Moscow and at the three U.S. consulates in Russia.
The Russian Foreign Ministry also said earlier that, as of August 1, the United States would be barred from using warehouses that it has used in Moscow and from a modest property in the capital's leafy Serebryanny Bor district that is used by U.S. Embassy mainly for events such as parties and barbecues.
That move appeared to be a direct response to the Obama administration's decision to seize two Russian diplomatic compounds, one in Maryland and one in New York State, when it expelled the 35 diplomats in December.
Putin surprised many people in both countries by declining to retaliate immediately over the expelled diplomats and seized properties. The restraint was widely seen as a gesture to Trump, who was due to take office within weeks and had repeatedly said that he wanted to improve ties with Moscow.
Putin said in the July 30 interview that the reduced U.S. diplomatic presence would be "quite painful" and added that he did not expect ties with Washington to improve "any time soon."
"We have waited long enough, hoping that the situation would perhaps change for the better," he told the prominent Russian television host Vladimir Solovyov.
"But it seems that, even if the situation is changing, it's not for any time soon," Putin said.