“They got away with it. Everyone knew it was Russia. I mean, the [alleged] assassin Andrei Lugovoi was promoted and put into the Duma,” Lautman said, adding: “And with Skripal, I will never forget (Prime Minister) Theresa May giving Russia an ultimatum to provide answers. And they delivered another dead body within 48 hours – Nikolai Glushkov.”

Glushkov, a Putin critic, was living in the UK after being granted political asylum. He was found dead in his home in London a week after the Salisbury poisoning. A spokesperson for the Metropolitan Police told CNN that a post-mortem found that he had been strangled and that a murder investigation led by detectives from the Met’s Counter Terrorism Command continues. No arrests have been made and no motive established.

Thornton said that NATO was reluctant to blame the Skripal poisoning directly on Putin and the Russian state because of the risk of escalation and pushing Russia into being a “complete adversary.”

“(They) would kind of said maybe it was a rogue GRU operation, was Putin really behind it? There was an element of ‘let’s not go too far, because we don’t want to lose Putin completely,’” he said.

“Now that’s completely off the table,” he added.

While many of the more high-profile attacks – the Litvinenko and Skripal poisonings, for example – are thought to have been approved or even ordered directly by Putin, the desire to hurt the West cuts through the Russian political establishment, analysts say.

The people known as siloviki — Russia’s most powerful men (they are almost exclusively men) who rose to power through the ranks of the Soviet and Russian security services – see the relationship between the West and Russia as a zero-sum game. Russia can only be strong if the West and NATO are weak.

“Russia has always been antagonistic towards the West,” Thornton said. “It goes way back to tsarist times, the idea of the West being a threat, that the West wants to do Russia down, to make Russia a smaller state, a weak state … so whoever you put in power in the Kremlin, there’s still going to be this mindset that the West is in essence the enemy.”

Lautman agreed, adding that the current establishment’s hatred towards the West stems partly from the events following the fall of the Soviet Union in the early 1990s, when Russia had to be bailed out by the West after its economy collapsed.

The idea that Russia’s aggression will end with the eventual demise of Putin is the West’s “biggest mistake,” she said, predicting successive leaders will continue to see the West as an enemy until the country gives up the idea of Russian imperialism – which won’t happen easily.

“And Europe, and the whole international community who wants global stability, they need to understand that Russia is at war with us and that they will continue escalating unless we start acting.”