Russian President Vladimir Putin said Sunday that the U.S. diplomatic missions in Moscow and elsewhere in the country will have to reduce their staffs by 755 people, signaling a significant escalation in the Russian response to American sanctions over the Kremlin's intervention in the 2016 presidential election.

The United States and Russia have expelled dozens of each other's diplomats before — but Sunday's statement, made by Putin in an interview with the Rossiya-1 television channel, indicated the single largest forced reduction in embassy staff, comparable only to the closing of the American diplomatic presence in the months following the Communist revolution in 1917.

In the interview, Putin said that the number of American diplomatic and technical personnel will be capped at 455 — equivalent to the number of their Russian counterparts working in the United States. Currently, close to 1,200 employees work at the United States' embassy and consulates in Russia, according to U.S. and Russian data.

"More than a thousand employees — diplomats and technical employees — have worked and are still working in Russia these days," Putin told journalist Vladimir Solovyov on a nationally televised news show Sunday evening. "Some 755 of them will have to terminate their activity."

Putin's remarks came during a three-and-a-half-day trip by Vice President Mike Pence to Eastern Europe to show U.S. support for countries that have chafed at interference from Moscow — Estonia, Georgia and Montenegro.

"The president has made it very clear that Russia's destabilizing activities, its support for rogue regimes, its activities in Ukraine are unacceptable," Pence said when asked by reporters in Tallinn, Estonia, whether he expects Trump to sign the sanctions. "The president made very clear that very soon he will sign the sanctions from the Congress of the United States to reinforce that.

"As we make our intentions clear, we expect Russian behavior to change."

On Sunday night, a senior State Department official said, "The Russian government has demanded the U.S. Mission to Russia limit total Mission staffing to 455 employees by September 1. This is a regrettable and uncalled for act. We are assessing the impact of such a limitation and how we will respond to it."

The Kremlin had said Friday, as the Senate voted to strengthen sanctions on Russia, that some American diplomats would be expelled, but the size of the reduction is dramatic. It covers the main embassy in Moscow, as well as missions in St. Petersburg, Yekaterinburg and Vladivostok.

The U.S. Embassy in Russia has been unable to provide exact numbers on the number of staff it employs in Russia. But according to a 2013 review by the State Department, of 1,200 employees of the American Mission in Moscow, 333 were U.S. nationals and 867 were foreign nationals, many of them probably local Russian support staff, including drivers, electricians, accountants and security guards. That would suggest that the majority of the 755 who must be cut would not be expelled from the country.

"This is a landmark moment," Andrei Kolesnikov, a journalist for the newspaper Kommersant who regularly travels with Putin and has interviewed him extensively over the past 17 years, told The Washington Post in an interview Friday. "His patience has seriously run out, and everything that he's been putting off in this conflict, he's now going to do."

The Russian government is also seizing two diplomatic properties — a dacha, or country house, in a leafy neighborhood in Moscow and a warehouse — following the decision by the Obama administration in December to take possession of two Russian mansions in the United States.

The move comes as it has become apparent that Russia has abandoned its hopes for better relations with the United States under the Trump administration.

"I think retaliation is long, long overdue," deputy foreign minister Sergei Ryabkov said Sunday on ABC's "This Week with George Stephanopoulos."

"We have a very rich toolbox at our disposal," Ryabkov said. "After the Senate ... voted so overwhelmingly on a completely weird and unacceptable piece of legislation, it was the last drop."

Hours later, Putin said during his evening interview that he expected relations between the United States and Russia to worsen and that Russia was likely to come up with other measures to counter American financial sanctions, which were passed by the House and Senate last week and which President Trump has said he will sign.

The reduction in U.S. diplomatic and technical staff is a response to President Obama's expulsion of 35 Russian diplomats in December in response to the alleged Russian hacking of the mail servers of the Democratic National Committee. The United States also revoked access to two Russian diplomatic compounds on Maryland's Eastern Shore and on Long Island. American officials said they were used for intelligence collection.

It is not yet clear how the State Department will reduce its staff in Russia. Some of the local staff were hired to help with a significant expansion of the U.S. embassy compound in Moscow.

After the State Department, the next largest agency presence in Moscow in the 2013 review belonged to the Defense Department, which had 26 employees working for the Defense Intelligence Agency (20 of them U.S. nationals) and 10 working for the Defense Threat Reduction Agency (of whom nine were U.S. nationals).

The Library of Congress had two U.S. staff and two foreign staff, and NASA had eight U.S. staff and four foreign staff members.

There were 24 Marine security guards.

The move increases the likelihood of new, perhaps asymmetrical reprisals by the United States in coming days.

Michael McFaul, former ambassador to Russia, tweeted Sunday: "If these cuts are real, Russians should expect to wait weeks if not months to get visas to come to US."

Ashley Parker in Tallinn, Estonia, and Madhumita Murgia in Washington contributed to this report.