The Prime Minister will meet her Cabinet today buoyed by the success of her response to the Salisbury poisoning, with more than 130 Russian diplomats being expelled from capital cities across the globe.
Suspected intelligence officers in Canada, Ukraine, Albania, Macedonia and a number of EU states will be ejected, with some 60 Russians to be kicked out of the US.
It is part of a co-ordinated international response to the nerve agent attack on ex-Soviet double agent Sergei Skripal and his daughter Yulia earlier this month.
Some 23 nations have taken action, following the UK’s lead.
Australia became the latest country to back Britain by expelling two diplomats, after Theresa May told the Commons the West had united behind the “largest collective expulsion of Russian intelligence officers in history”.
“I have found great solidarity from our friends and partners in the EU, North America, NATO and beyond over the last three weeks as we have confronted the aftermath of the Salisbury incident,” the Prime Minister said.
“Together we have sent a message that we will not tolerate Russia’s continued attempts to flout international law and undermine our values.”
Conservative, Labour and SNP MPs have all praised Mrs May over her approach to the attack, and Tony Blair has complemented her for doing “the right thing” and having “handled it impressively”.
But the Western response has continued to draw a furious response from the Kremlin, which has accused the UK and its allies of “blindly following the principle of the Euro-Atlantic unity to the detriment of common sense, the norms of civilised inter-state dialogue and the principles of international law”.
Dmitry Peskov, spokesman for Vladimir Putin, has hinted Moscow will respond to the expulsions, having already ordered 23 British diplomats to leave.
On Twitter, the Russian Embassy in Washington DC asked followers to vote on which US consulate should be closed, listing Vladivostok, St Petersburg and Yekaterinburg as options.
President Vladimir Putin has maintained Russia was not involved in the poisoning of the Skripals, branding the accusations levelled at him as “nonsense”.
Mrs May revealed during her Commons address that the pair remain in a coma and are unlikely to recover, adding that some 130 other people had potentially been exposed to the nerve agent.
“This shows the utterly barbaric nature of this act, and the dangers that hundreds of innocent citizens in Salisbury could have faced,” the Prime Minister said.
Australian Prime Minister Malcolm Turnbull described the attack as “shocking”, while Danish counterpart Lars Lokke Rasmussen said it was “completely unacceptable”.
The White House branded it a “brazen action” and said the move to expel 60 Russians would make the country safer.
“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,” said a spokesman.
“With these steps, the United States and our allies and partners make clear to Russia that its actions have consequences.”