Former double agent Sergei Skripal and his daughter will have been whisked off to a safe house as far away as New Zealand, experts have said.
The retired Russian intelligence officer, brought to Britain in a spy swap in 2010, would have thought he was safe after coming to the UK, due to a "gentleman's agreement" that countries don't go after defectors exchanged in swaps.
But the novichok attack on the 66-year-old - which was yesterday blamed on two agents of Russia's GRU intelligence service - means he and his daughter, who was also attacked, will now have to be closely looked after by Britain and her allies.
It was previously reported that the CIA would offer to settle the pair into a new life with new identities in the US, to keep them from any further assassination attempts.
Experts say it is likely they will have been moved to one of Britain's 'Five Eyes' allies; the US, Canada, Australia and New Zealand.
Chris Phillips, the former head of the National Counter Terrorism Security Office, told MailOnline: "We trust those countries to do things the right way. No expense will be spared."
The pair will have been given a house and monthly allowance, as Skripal was in the UK, but will now be given protection and surveillance following the Salisbury attack, Phillips added.
The father and daughter may be split up to prevent any suspicion of who they are, but changing their appearance may be difficult due to pictures having been published by the world's media.
Skripal may now have to be more careful when talking about his past, after joking with friends in Salisbury that he was a spy.
His former taxi driver Adam Blake said: "He would look each way, as if joking, and say, 'I'm a Russian spy'. He would say it to all the drivers and nobody ever believed him.
"I would often see him standing around town in doorways too, looking around suspiciously as if he was really trying to portray the spy image."
Skripal had settled into Salisbury, joining a Railway Social Club, drinking in some of the city's pubs and buying scratch cards at his local newsagent.
He has been regularly visited by his family, who travelled from Russia and even posted pictures of him in his new life on social media.
In a video released a month after the attack, Yulia Skripal said she hoped to return to Russia in the future, but insisted she did not need the help of the country's embassy.
Yesterday's revelations, which go much further to proving Russian involvement in the attack, may force her to change her plans about going back to her homeland.
She will now probably be advised to steer clear of social media or sending emails, due to fears it could give away her location, experts have said.
What are the "Five Eyes" countries?
The Five Eyes intelligence pact formerd when other countries joined the BRUSA agreement between British and US intelligence agencies which came after the end of the Second World War.
Canada joined in 1948 and Australia and New Zealand became part of the agreement in 1956.
It is understood the countries do not share everything they know, but the agreement means they do have a closer relationship than with other Nato members.
The pact was threatened in the aftermath of the Manchester bombings last year, when US agencies leaked pictures of the scene passed to them by the British to the media.
US President Trump condemned the leak and said: "There is no relationship we cherish more than the special relationship between the United States and the United Kingdom.'