The prime minister used a speech at the Lord Mayor’s Banquet in London to praise international collaboration after the UK blamed Moscow for the incident.
She condemned what she branded “the reckless use of a chemical weapon on our own streets” by Russia’s GRU intelligence agency and called on western authorities to continue to stand together.
The prime minister said: “Together with our allies, in response to the attack in Salisbury, we coordinated the largest ever collective expulsion of Russian intelligence officers, fundamentally degrading Russian intelligence capability for years to come.
“And our law enforcement agencies, through painstaking investigations and cooperation with our allies, produced the irrefutable evidence that enabled our Crown Prosecution Service to bring charges against those responsible.”
The UK accused the GRU of carrying out the poisoning of ex-spy Sergei Skripal and his daughter Yulia with Novichok in Salisbury in March.
Russia has also been blamed for the death of 44-year-old Dawn Sturgess and the poisoning of her partner Charlie Rowley, who are believed to have come into contact with Novichok discarded by the Skripals’ attackers.
Ms May hailed the efforts of Dutch government in thwarting Russian attempts to undermine international weapons bodies.
“In response to the activities of the GRU in Europe, through the cooperation of western security agencies, the Dutch government were able to prevent and expose Russian attempts to penetrate and undermine the Organisation for the Prohibition of Chemical Weapons,” she said.
“In these actions, we have seen the impact of international unity and a collective response to these threats.
“We have shown that while the challenge is real, so is the collective resolve of like-minded partners to defend our values, our democracies, and our people.”
But the prime minister indicated the UK is ready for better relations with Moscow.
“We remain open to a different relationship - one where Russia desists from these attacks that undermine international treaties and international security - and instead acts together with us to fulfil the common responsibilities we share as permanent members of the UN Security Council,” she said.
“And we hope that the Russian state chooses to take this path. If it does, we will respond in kind.”
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