The Russian TASS news agency reported that a group of 60 US diplomats along with their families had left the embassy compound on three buses and a minibus at 6:30 am local time (0330 GMT) on Thursday and headed toward the Moscow airport.
The Kremlin had set an April 5 deadline for the US envoys to leave the country, declaring the staffers personae non gratae for activities incompatible with their diplomatic status.
There has been a series of tit-for-tat diplomatic expulsions since Britain accused Russia last month of poisoning former Russian double agent Sergei Skripal and his daughter, Yulia, without offering any proof.
Russia has denied any involvement in the incident, which occurred on March 4 in the British city of Salisbury. The Skripals are being treated in a UK hospital.
The UK claims the nerve agent allegedly used in the poisoning was Novichok, which was developed in the former Soviet Union, basing its accusations against Moscow on that assertion.
Moscow says the substance could have originated in the countries studying Novichok, including the UK itself, Slovakia, the Czech Republic, and Sweden.
Following the poisoning incident, Britain expelled 23 Russian diplomats and their families, prompting Russia to send back as many British diplomatic personnel.
In an act of apparent solidarity with the UK, Washington announced its decision on March 26 to expel 60 Russian diplomats and close Russia’s Consulate General in Seattle.
A total of 150 Russian diplomats have been expelled from various Western countries, most of them from Britain and the US. Other countries include France, Germany, Canada and Poland, Australia, Ukraine, the Netherlands, Sweden, the Czech Republic, Finland, Lithuania, and Norway.
Russia has responded in kind.
On Wednesday, Russia called on the United Nations Security Council to hold a meeting to discuss Britain’s accusation that Russia was involved in the Salisbury incident.