Mr. Putin, in the television interview during which he announced the retaliatory move, said that Russian patience with waiting for relations to improve was at an end.
It was a major shift in tone from the beginning of this month, when Mr. Putin met Mr. Trump for the first time at the Group of 20 summit meeting in Hamburg, Germany.
Mr. Trump had talked during his campaign of improving ties with Russia and had praised Mr. Putin, and the Kremlin had expected the face-to-face meeting of the presidents to mark the start of a new era. The immediate assessment in Moscow was that the two had set the stage for better relations.
But then, in quick succession, came the expanded sanctions passed by Congress, Mr. Trumpâs indication that he would sign them into law and Moscowâs forceful retaliation.
In Washington, the State Department issued a statement saying that it was assessing the impact of the Russian measures and how it would respond. The United States Embassy in Moscow declined to comment.
Just as in 2014, when Russia reacted to the first Western sanctions imposed over the Ukraine crisis by banning many Western food imports, it seems that ordinary Russians will bear the brunt of the latest decision.
The bulk of the 755 people dismissed are likely to be Russian employees from the embassy in Moscow, as well as from the American consulates in St. Petersburg, Yekaterinburg and Vladivostok. It is not clear how many Americans might be expelled, if any.
A State Department inspector generalâs report in 2013, the last concrete numbers publicly available, said there were 934 âlocally employedâ staff members at the Moscow Embassy and three consulates, out of a total staff of 1,279. That would leave roughly 345 Americans, many of whom report regular harassment by Russian officials.
In Moscow, locally hired staff members reached at the embassy said the mood inside the walls of the large compound on the Garden Ring, one of Moscowâs main thoroughfares, was stunned confusion.
âEveryone is worried, and there is no information,â said one. âThere are so many rumors and no facts yet.â
The measures were the harshest such diplomatic moves since a similar rupture in 1986, in the waning years of the Soviet Union. At that time, Moscow forced 261 local staff members to quit, leaving the embassy mostly devoid of secretaries, drivers and other support staff.
âI heard from people who were here when that happened and how devastating it was at that time,â said the staff member, who spoke on condition of anonymity because embassy personnel are not authorized to talk to the news media.
Mr. Peskov said it was up to the Americans to decide how to reduce their staff to 455, matching the size of Russiaâs diplomatic staff in the United States, including those at the Russian Mission to the United Nations in New York.
Whereas the United States has long relied on local staff, the Russians tend to employ their own citizens as support staff. Mr. Peskov said the criterion was anyone considered to be on the staff, which would not include outsourced workers.
He denied that giving the Americans until Sept. 1 to reduce their staff was a bargaining tactic.
âWhen thereâs such a large-scale cut, it will be inhumane and inappropriate to demand it to be implemented within such a term that was given, for example, to our diplomats on the New Yearâs Eve,â he said.
In response to Russian hacking of the American election, President Barack Obama expelled 35 Russian diplomats in late December, giving them 72 hours to leave the country, and he ordered the seizure of two diplomatic country estates, which the United States said had been used for espionage as well as for recreation.
Mr. Putin did not respond at first, hoping for improved ties. But in this tit-for-tat response, Russia also blocked access starting Tuesday to a warehouse and a bucolic enclave along the Moscow River that the embassy has used for barbecues.
Congress passed the latest sanctions last week to punish Russia for interfering in the 2016 election, including by releasing hacked emails embarrassing to Hillary Clintonâs campaign. The law forces Mr. Trump to seek congressional approval before removing any sanctions.
Congress is also investigating the possibility of collusion between the Trump campaign and the Russian government. Mr. Trumpâs eldest son, Donald Trump Jr., has confirmed that he met with a Russian lawyer linked to the government who wanted to discuss removing an earlier round of sanctions.
Mr. Putin has denied any Russian interference in the American election, saying that anti-Russian sentiment in the United States was being used as a weapon in an internal political battle.
At the very least, the order from the Kremlin was expected to set back some functions at the embassy, like processing visas, which both sides had already slowed.
Many of those emerging from the visa section of the embassy on Monday suggested that the latest measures could only make a bad situation worse.
Vladimir Kruglov, a retiree who said he enjoyed touring national parks in the United States, said that until recently the visa process had taken a maximum of 20 days, but that there were now all kinds of extra procedures, including a monthâs wait for an interview.
Shavkat Butaev, 50, who works for a company that helps Russians get visas, said there had been a big leap in the number of rejections.
âIt was never like this before: 50 to 60 people get rejected every day, most of them young women,â he said. âI look at who has a green paper in their hands and that means they got a no.â
Oleg Smirnov, an 18-year-old who has been studying in the United States to become a psychiatrist, said he had hoped Mr. Trump would improve relations and he was worried about how the tensions might affect immigration policy.
âThese mutual sanctions look like a game played with water guns,â he said.