The Salisbury Novichok attack was done by Russia because it believed Britain was “weak and isolated” after the EU referendum, a former MI6 chief has said.
Sir John Sawers said he did not believe the Russians would have used a nerve agent in a US or German city in the same way they are alleged to have done in Salisbury.
He told BBC Radio 4’s The World at One: "They thought they could pick on Britain and bully us because we were looking weak.
"Actually Theresa May and her Government responded very strongly and forcefully to the Skripal attack but it was only because we were able to carry our European partners, the Americans and others, with us.
"It was through engagement with others that we were able to push back and have a credible response to the Skripal attack."
Former Russian spy Sergei Skripal was targeted in an attempted assassination in March, for which the Government blamed on the Russian GRU military intelligence agency. The Kremlin denied the allegations.
'The West is fragmented'
Salisbury Novichok poisoning suspects shown on CCTV at Salisbury train station
Sir John also suggested that Britain’s diplomatic power would be weakened by leaving the European Union in March 2019.
He said: "Our strength in the world has come from our ability to work with both the United States and our European partners.
"The more influence we have with the European Union, the more weight we have with America and vice versa.
"The Americans are to some extent walking away from their relationship with Europe, the transatlantic relationship, and we are walking away from the European Union. The West is fragmented."
He added: "What we are doing is losing traction both in Washington and in Europe, and that will make Britain less influential on the world stage."