Russia is facing the expulsion of dozens diplomats from America and Europe as key allies rallied behind Britain over the Salisbury nerve agent attack.
The United States led the way with the announcement that 60 suspected Russian spies have been given seven days to leave the country.
In Brussels, European Council president Donald Tusk said that 14 member states were expelling diplomats in a co-ordinated show of support for the UK.
Today 14 EU Member States decided to expel Russian diplomats as direct follow-up to #EUCO discussion last week on #SalisburyAttack. Additional measures including further expulsions are not excluded in coming days, weeks.
-- Donald Tusk (@eucopresident) March 26, 2018
Among the EU member states taking action were Germany and Poland - which each said they were expelling four diplomats. Lithuania and the Czech Republic have each ordered three diplomats to leave while Denmark is expelling two.
The expulsions were welcomed by Foreign Secretary Boris Johnson who said on Twitter: "Today's extraordinary international response by our allies stands in history as the largest collective expulsion of Russian intelligence officers ever & will help defend our shared security. Russia cannot break international rules with impunity."
Today's extraordinary international response by our allies stands in history as the largest collective expulsion of Russian intelligence officers ever & will help defend our shared security. Russia cannot break international rules with impunity
-- Boris Johnson (@BorisJohnson) March 26, 2018
The moves come after EU leaders last week backed Theresa May's assertion that there was "no plausible alternative explanation" other than Russia was responsible for the attack on former double agent Sergei Skripal and his daughter Yulia.
In addition to the expulsions, the White House said that the US was also closing the Russian consulate in Seattle "due to its proximity to one of our submarine bases and Boeing".
Statement on Expulsion of Russian intelligence officers. pic.twitter.com/4uCzMOMG3f
-- Sarah Sanders (@PressSec) March 26, 2018
A White House statement said: "The United States takes this action in conjunction with our Nato allies and partners around the world in response to Russia's use of a military-grade chemical weapon on the soil of the United Kingdom, the latest in its ongoing pattern of destabilising activities around the world.
"Today's actions make the United States safer by reducing Russia's ability to spy on Americans and to conduct covert operations that threaten America's national security.
"With these steps, the United States and our allies and partners make clear to Russia that its actions have consequences."
Danish prime minister Lars Lokke Rasmussen tweeted: "Russia has gone too far. An assassination attempt in a European city with a Russian nerve agent is completely unacceptable."
Russia has gone too far. An assassination attempt in a European city with a Russian nerve agent is completely unacceptable. The UK has our full support. Denmark will expel two Russian diplomats in our joint European response to the #SalisburyAttack. #dkpol
-- Lars Løkke Rasmussen (@larsloekke) March 26, 2018
A German foreign ministry statement said the expulsions were "a strong signal of solidarity with Great Britain and signals the resolve of the Germany government not to leave attacks against our closest partners and allies unanswered".
The ministry added that the move was also a response to the recent cyber attacks against German government networks, "which according to information so far is highly likely to be attributable to Russian sources."
The expulsions came after Britain expelled 23 undeclared intelligence officers - prompting the tit-for-tat expulsion by the Russians of the same number of UK diplomats.