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 President 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. Trump’s indication that he would sign them into law and Moscow’s 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 general’s report in 2013, the last concrete numbers publicly available, said there were 934 “locally employed” 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 Moscow’s main thoroughfares, was stunned confusion.
“Everyone is worried, and there is no information,” said one. “There are so many rumors and no facts yet.”