US Ambassador to Russia John Tefft has expressed his "strong disappointment and protest" over the countermeasures regarding a US diplomatic compound and US diplomats in Russia.
"There is currently 600-700 [personnel] now, and the cut will be very painful to them," the source said, pointing out that the reduction would affect 200-300 US staff members.
The bill, which is yet to be approved by US President Donald Trump, has already prompted criticism within the European Union. France and Germany have so far spoken out against the bill that the US House passed overwhelmingly on Tuesday as one that adversely affects European industries while advancing US commercial interests.
On Thursday, Russian President Vladimir Putin said that Russia is behaving patiently amid sanctions, but time will come when Moscow will be forced to respond to arrogance, adding that if adopted, the US anti-Russia sanctions bill would be an "extra-cynical move."