It is the biggest concerted action against Russian intelligence networks by the west since the Cold War.
More than 100 Russian diplomats have been expelled from over 20 western nations in response to the nerve agent attack in Salisbury on former Russian intelligence officer Sergei Skripal.
Sixteen EU member states — as well as Ukraine, Canada and Albania — joined Britain in banishing Russian diplomats.
The US alone expelled some 60 diplomats and ordered the closure of the Russian Consulate in Seattle.
"The poisoning in the UK that has kind of led to today's announcement was a very brazen action. It was a reckless action," said White House spokesman Raj Shat. "It endangered not just two individuals who were poisoned, but many civilians, many innocent civilians. And this is not the type of conduct that the United States or allies can accept."
Russia, however, branded the move "a provocative gesture" and said it would retaliate in kind.
Vassily Nebenzia, Russian Ambassador to the UN said:
"That`s a very unfortunate and very unfriendly move... It was protested in Washington by the ambassador when he was invited to the State Department. And I`m sure it will be protested and is already being protested."
The Russian foreign ministry said the expulsions were based on alliances rather than evidence. EU leaders say it is highly likely Russia was behind the attack on Skripal and his daughter