NATO expelled seven Russian diplomats and vowed to reject accreditation requests from three others as countries around the world united against Moscow.
A total of 26 countries have expelled 143 Russian officials, with the Foreign Office hailing its allies for standing “shoulder to shoulder” with the UK and sending the “strongest signal to the Kremlin” following the nerve agent attack in Salisbury.
“Russia cannot break international rules with impunity,” it added in a tweet on Tuesday.
Theresa May praised the “unprecedented series of expulsions” across the globe, with Belgium becoming the 26th country to take action, expelling one diplomat.
The Prime Minister’s spokesman said Mrs May had told ministers the action against Russia was “an unprecedented series of expulsions that has demonstrated to the Kremlin that we will not tolerate their attempts to flout international law, undermine our values or threaten our security”.
She added: “It is also important to note that our partners are not only taking these measures out of solidarity with the UK, but also because they recognise the threat that these Russian networks pose to the security of their own countries and the pattern of Russian aggression which has affected us all.”
A spokesperson for Belgian Prime Minister Charles Michel said it was “very likely” Russia was responsible for the Salisbury nerve agent attack.
They added: “Given the gravity of the events in Salisbury and the high probability of Russia’s involvement in this attack, we consider this measure to be fully justified.
“The Russian ambassador will be notified about this decision within 48 hours. The person concerned will have 14 days to leave Belgium.”
NATO secretary general Jens Stoltenberg said the move against the Russian diplomats sent a clear message to Moscow that its actions “had costs”.
He said: “What triggered this was the Salisbury attack. But it is part of a broader response by NATO allies to a pattern of unacceptable and dangerous behaviour by Russia.
“We have seen the illegal annexation of Crimea, we have seen the destabilisation of eastern Ukraine, we have seen cyberattacks, we have seen hybrid tactics, we have seen Russia investing heavily in modern military equipment and the willingness to use military force against neighbours.”
Others expelling diplomats on Tuesday included Ireland. Its foreign minister, Simon Coveney, said the use of chemical weapons was “shocking and abhorrent”.
Vladimir Putin’s spokesman Dmitry Peskov has said Russia will proceed with a “principle of reciprocity”. Moscow has already ordered the expulsion of 23 British diplomats.
The Russian foreign ministry said: “This provocative gesture of notorious solidarity with London, made by countries that preferred to follow in London’s footsteps without bothering to look into other circumstances of the incident, merely continues the policy of escalating the confrontation.”