The Government has promised a "robust" response if Russia is behind the Salisbury nerve agent attack but what could be imposed on Vladimir Putin's regime?
:: Expelling diplomats
There have been calls to expel Russia's ambassador to the UK if the Kremlin ordered the poisoning of former spy Sergei Skripal and his daughter Yulia.
Sir Christopher Wrey, the former UK ambassador to the US who has previously worked in Moscow, told Sky News: "You could, if this is proven, take advantage of this horrible case and not only expel the ambassador, but drain the swamp of all these guys MI5 are tagging around the streets of London and wherever."
He added that the UK's response after the death of former Russian spy Alexander Litvinenko in 2006 – when four Russian diplomats were expelled – "probably was too weak".
:: Avoiding Russia's World Cup
Foreign Secretary Boris Johnson has suggested the UK's involvement at the World Cup in Russia this summer could be affected by the nerve agent attack.
"I think it would be very difficult to imagine that UK representation at that event could go ahead in the normal way and we would certainly have to consider that," he told the House of Commons.
It was later clarified Mr Johnson was referring to the possibility that officials, dignitaries and ministers may not attend the World Cup, not that England would boycott the tournament.
:: Sanctions
Mr Johnson has also threatened fresh sanctions against Russia if it was responsible for the Salisbury poisoning.
Britain has already backed tough UN and EU sanctions on Russia's economy to oppose its annexation of Crimea and intervention in Ukraine.
The sanctions targeted Russia's state finances, energy and arms sectors, which are managed by the powerful elite around President Putin.
:: Imposing 'The Magnitsky Act'
The Government has introduced measures in the Criminal Finances Act, inspired by America's Magnitsky Act, to allow the assets of international human rights violators to be frozen.
The US law was named after whistle-blowing lawyer Sergei Magnitsky, who died in a Moscow detention centre in 2009 after attempting to reveal a massive tax fraud against his British-based investment firm and the Russian state.
The 37-year-old father-of-two was held for almost a year without trial and denied medical treatment.
Home Secretary Amber Rudd indicated that the Salisbury incident may prompt further action.
"The Sanctions Bill is at the moment before the committee and I know there are people who are talking about wanting to put down amendments at report stage," she said.
"Of course what we have seen happening in the past few days may bring this more to the front."
:: Ending diplomatic ties
Former Tory minister Nick Bold has urged Britain to break off diplomatic ties with Russia in the wake of the Salisbury poisoning.
More from Salisbury spy
He said: "I do not see how we can maintain diplomatic relations with a country that tries to murder people on British soil and puts the lives of British citizens at risk.
"It's time for us to turn tough talk into action."
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