As appears to be the case with Sergei Skripal in Britain on Sunday, Russian intelligence services like to use innovative but brutal weapons to assassinate defectors abroad.

They do so in order to send a message both to serving intelligence officers and to other defectors who have thus far eluded their grip — a message that Russia never forgives and never forgets those who betray it.

Yet for the Russian government’s intelligence services, killing isn’t enough. Where a car crash, shooting, car bomb, or knife attack would accomplish the same physical outcome as spraying someone in the face with a nerve agent, for example, it would carry less symbolism of angry relentlessness. It would carry a message that sat less darkly alongside the bodies.

Instead, the Russian intelligence services want those who have betrayed them to always fear their every waking moment. They want their enemies, forgiven on paper but never in reality, to walk, as Skripal did, through a British town and wonder whether brutal death might lurk just around the corner. Or to attend afternoon tea and contemplate whether their piping drink might actually be radioactive. Or to question if the man walking down the street might be heading home for dinner with his family or carrying a death warrant signed by President Vladimir Putin.

This is the way the Russian intelligence community operates: brutally and relentlessly. In his book Aquarium, former Glavnoye Razvedyvatel'noye Upravleniye foreign intelligence officer and defector Viktor Suvorov explains how newly appointed Soviet-era GRU officers were shown a video of a defector being thrown into an oven alive. From the very start, those who wear the emblems of the GRU, Federal'naya Sluzhba Bezopasnosti, Sluzhba Vneshney Razvedki, and Spetssvyaz are given no illusions as to the lifetime expectation of loyalty and the corollary consequences for failure.

Thus, whatever the form, Russian assassinations of defectors use tactical brutality in pursuit of a broader strategic impact: inculcating the fear and obedience of others.