Vladimir Putin’s spies have a dizzying variety of weapons at their disposal. This week Britain learned of a new one: Novichok, a nerve agent used in an attempt on the life of a former Russian intelligence officer in Salisbury. But Putin’s real power, far more dangerous than all the rockets and poisons in his arsenals, lies in his toxic ability to corrode truth.

Putin lies, barefacedly and repeatedly. So do his acolytes. Even when the forensic evidence is massive and incontrovertible, Putin tells palpable falsehoods with easy fluency. In March 2014 he insisted that there were no Russian troops in Crimea, claiming that ‘anyone could buy’ Russian military uniforms. Within a month, he publicly thanked the troops that had participated in the annexation. With equal ease, he reversed himself on the presence of regular Russian forces in Eastern Ukraine — after two years of denying they were there, Putin casually acknowledged the truth in 2016.

The point is that lying itself is the message. Putin’s lies are not about concealment but rather about his ability to assert his power over truth itself. He says, now, that the Kremlin had nothing to do with the attack on Sergei Skripal — and if British intelligence officers are convinced that the nerve agent used could only have come from a laboratory tightly controlled by the Russian government, well, that’s their problem. If the British want an explanation for what happened in Salisbury — by midnight on a Tuesday or any other time — why would they come to him? Putin doesn’t need to be honest. He believes that he controls the truth. He can make his own reality.

That belief in the ability to control any narrative simply by deceit is the root of Putin’s hubris — and that of the proxies under his authority but not always his command. The pattern has been repeated with increasing frequency over recent years: whether over the shooting down of a Malaysian Airlines Boeing by a Russian army BUK rocket, the systematic campaign of state-sponsored doping of Russian athletes at the Sochi Olympics, US election hacking or, now, the attempted murder of the former military intelligence colonel Sergei Skripal. The Kremlin believes that its people will never be brought to account for their actions.

It doesn’t matter how ridiculous the conspiracy theory is — as long as it exculpates Russia. This week the Russian state TV news anchor Sergei Kisilev claimed that Skripal was murdered by MI6 in a plot to whip up Russophobia and boost Theresa May’s flagging poll numbers. Margarita Simonyan, founder and head of the Kremlin-funded propaganda channel RT (formerly Russia Today), wrote a sarcastic post on her Facebook page imagining ‘some special guys’ in the West ‘drinking iced coffees and thinking, what kind of stunt can we pull before the elections to make Russians dislike Putin?’ Does Simonyan really believe what she is saying? Does Kisilev? Does the foreign minister Sergei Lavrov really believe that he is speaking the truth when he denies the Assad regime’s chemical weapons attacks?

It’s a question I ask myself very often in Russia as I speak to apparently intelligent, well-informed and worldly Russian officials who spout unbelievable nonsense. The recent Oscar-winning documentary film Icarus, an extraordinary exploration of Russia’s sports doping scandal, gives an important clue to what goes on in these people’s minds.

The film’s eccentric hero, Gennady Rodchenkov, was simultaneously head of both Russia’s anti-doping agency and of its official doping programme. His job was to give performance-enhancing drugs to Russia’s Olympic team — and to help them conceal their fraud at the highest forensic level. A fan of Orwell’s Nineteen Eighty-Four, Rodchenkov explains his countrymen’s easy attitude to lying in terms of ‘doublethink’. To simultaneously hold two entirely contradictory positions in their mind and believe them both to be true is part of Russian culture, he muses. To lie well is a virtue.

Moreover, the cynicism is so penetrating that most Russians seem to believe that everyone else behaves exactly as they do — but are simply more hypocritical. ‘Everybody does it’ is the universal Russian justification of last resort, usually followed by a false equivalence. ‘The West kills its own citizens abroad in drone strikes’ in justification of Skripal. ‘The West invaded Iraq and Kosovo without UN approval’ in support of the annexation of Crimea. And so on.

The problem for the rest of the world is that Putin goes much further than just lying. The Kremlin has actively, through the concerted efforts of his propaganda machine, mounted a systematic assault on the very idea that truth itself can exist anywhere. For years the Kremlin’s constant message to captive Russian audiences — and increasingly to western readers of the tweets and posts created by its army of trolls — is that the world is impossibly complex and unknowable. The principle is that the West’s ignorance — or at least confusion — is Russia’s strength.

‘How do you know?’ Putin recently said of election hacking. ‘I don’t know.’ That’s the key to the Kremlin’s message, neatly encapsulated in the slogan of RT, recently plastered on the London Underground: ‘Question more.’ RT’s coverage has become a notorious home for conspiracy theorists — including 9/11 Truthers — and its goal is precisely to spread doubt. The basic line of attack is to undermine the idea that news reporting can be objective, the notion that politicians can be sincere, or elections honest.

As the Mueller indictment showed, Russian election trolls were equal-opportunity disrupters, promoting both Bernie Sanders and Donald Trump on the grounds that both would be bad for Hillary Clinton and throw the American body politic into crisis. The same principle has long applied to Russia’s consistent propaganda support for European nationalist movements, from Scottish and Catalan independence to Brexit.

Cynicism is indeed contagious. Fake news is the fuel of division and the solvent of democracy. But it would be a mistake, for instance, to ban RT from British airwaves. The principle of asymmetric warfare is to goad your stronger opponent into self-defeating acts of overreaction — and allowing Russia to push us into censorship would be just such an own goal. Our own tendency to question our values, our leaders and our news has made a small space for Putin’s toxic, nihilistic message to take root among the gullible and the paranoid. But it is important to remember how small and marginal the real influence of Russia’s propaganda efforts remains. They are heinous in their intent, not their effect.

Russian murder sprees in the UK are a different matter. Theresa May called the Skripal attack ‘an unlawful use of force by the Russian state against the United Kingdom’ and announced 23 diplomatic expulsions to signal Britain’s displeasure. But as she knows, Russia is likely to expel a similar number from Moscow in the ritual Cold War manner. Her whole response — saying she’d ‘develop proposals’ to go after Russian spies, to freeze assets only if they ‘threaten the life or property’ of Brits — served to underline how few options she has at her disposal. The truth of the matter is that there is actually nothing that Britain alone can do that will not, at least in the short term, actually strengthen Putin.

Since 2014, Putin has cast himself as a wartime leader, protecting his people against successive waves of western aggression and falsification aimed at keeping Russia down. He plays the part of a man traduced and baited by wild Russophobic accusations — but nonetheless remaining reasonable. ‘Listen, let’s sit down calmly, talk and figure things out,’ he told NBC. Yet just days later, Putin made a new (but actually largely fictional) generation of super-fast nuclear weapons the centrepiece of his state-of-the-nation speech. The calumnies and sanctions of foreigners are, in this narrative of Putin as Defender of the Motherland, just measures of his growing power, and of their fear of mighty Russia.

That fantasy of might has distracted a lot of Russians from their country’s economic decline. Last year, a study by the Carnegie Moscow Centre showed how successive waves of sanctions following the Crimea annexation have depressed Russia’s economy and locked it into a kind of low-growth trap. But economic stagnation has not dented Putin’s ratings, which stand at a steady 80 per cent — higher, in fact than during the peak of Russia’s oil-fuelled boom before 2014.

As Putin sails into six more years in the Kremlin, the West is at a loss for what to do next. Donald Trump has offered words of support to Theresa May, but not much more. She could freeze the assets of individual wealthy Russians, which would inconvenience some members of the Moscow elite. But it will not harm the very top satraps of the Kremlin and its security services. Most of those have already been forced, both by earlier rounds of sanctions and by Putin himself, to either bring their money back to Russia or bury it deeper offshore.

Mrs May’s security council was told on Wednesday that Skripal was poisoned in a way that was deliberate: that the rare nerve agent used was intended to be a ‘-calling card’ of the FSB, and that it is pretty much impossible for the poison to have got out without top-level authorisation.

But there is another, even more worrying possibility that the UK seems to have overlooked — that the FSB or GRU or parts thereof were acting on their own. Not in the sense of agents going rogue, but more in the sense that Russian spooks assume a carte blanche to pursue traitors as they see fit. And well they might: the Russian parliament authorised the liquidation of terrorists and ‘enemies’ overseas in 2006. And Putin gave tacit authorisation to these operations back in 2010 when Skripal and ten other imprisoned US and British agents were exchanged. He promised that these ‘traitors … would choke on their 30 pieces of silver’.

But the sheer amateurishness of the Skripal attack, with such spectacular collateral damage not only to the people of Salisbury but to Russia-UK relations, is more suggestive of a bungling group of Russian spooks on a mission of revenge. Novichok is extremely deadly, easily detectable, easily identifiable — the exact opposite of a stealth poison like polonium, which doctors spent 22 days trying to identify after it had been used to kill Alexander Litvinenko.

So what next? Britain isn’t really sure: sanctions have been imposed and the govern-ment will have to wait for Russia’s reaction. Putin might even be right in protesting innocence: one thing he does care deeply about is giant set-piece sporting events like the World Cup: he has invested billions to make it a success. It’s far from clear why he would tarnish that vast effort to execute a single retired spy. But the problem with being a serial liar is that nobody believes you even when you’re right. In the end, Putin’s culture of lies is most toxic to Russia’s own interests.