Any evidence that the mystery illness of Sergei Skripal and his daughter Yulia was a Russian state-sponsored assassination attempt would plunge UK-Russian relations, already at a postwar low, even further into the deep freeze.
Despite heated denials of any involvement by Russia, links between London and Moscow were already straining on Tuesday.
As the Russian embassy accused the British media of “demonising” Russia, Boris Johnson, the foreign secretary, told parliament that the UK would respond “robustly” if any Russian link were established, and would look again at its sanctions regime.
Britain has for more than a decade tried to prevent its deteriorating political relationship with Moscow from damaging the extensive business links with Russia, which have seen hefty investment flows in both directions.
Some critics argue that the failure to respond more forcefully to earlier outrages, such as the fatal radioactive poisoning of Alexander Litvinenko, the former KGB officer, in 2006 and the mysterious death of Alexander Perepilichny, a whistleblower, in 2012, have emboldened Moscow.
Bill Browder, chief executive of Hermitage Capital and an outspoken critic of Russian president Vladimir Putin, said that Britain had created an environment where the “Kremlin feels it has the green light to carry out hits on UK soil without any consequences”.
“So there is a deep need to create real, meaningful consequences,” he added.
James Nixey, head of the Russia and Eurasia programme at the Chatham House think-tank, said Britain was partly “compromised” by having business interests in Russia “which affect the UK balance of payments”.
“The calculation has always been that the extent to which we are compromised outweighs the national security threat, because pension [funds] are invested in companies which are perhaps overexposed in Russia, and if we put that at risk then assets could be expropriated,” Mr Nixey said. “But the question is what is the straw that breaks the camel’s back?”
If the UK decided that Russia had crossed a line with the latest incident, potential measures could include tougher checks on the provenance of Russian money used to acquire property or assets in the UK, and on Russian listings on the London stock market.
Another could be subjecting senior Russian officials, some of whom own property in London, and pro-Kremlin business tycoons based in Britain to greater scrutiny. The government could go even further and seize properties of Putin-connected businesspeople in the UK.
Unexplained wealth orders, a legal tool created by the 2017 Criminal Finances Act that empowers UK law enforcement to seize the proceeds of “grand corruption”, could be used, Mr Browder said.
“There is no need for new legislation,” said Vladimir Ashurkov, a London-based ally of Alexei Navalny, the Russian opposition leader.
“It just takes political will to apply whatever laws are available in the UK to stem the flows of dirty money, which feed the system of political and economic corruption that enables Putin and his clique to carry out these terrorist acts abroad.”
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