Simon Jenkins asks whether there is a moral difference between drone strikes against British citizens fighting with Islamic State in Syria and the apparent assassination attempt against Sergei Skripal in Salisbury (We’re guilty in Syria, yet rage over Salisbury, 9 March).

Perhaps I can explain. Reyaad Khan and Junaid Hussain were actively planning terror attacks in the UK, and, in the words of the parliamentary committee report, posed a “very serious threat” to this country (Briton killed in drone strike on Isis, 26 April 2017.

Skripal, on the other hand, had already been punished in Russia for espionage, then pardoned and released as part of a prisoner exchange with the US. He spent the rest of his life with no access to state secrets, shopping for Polish sausages and buying scratchcards (Report, 7 March). The killings in Syria were preventative, the attack on Skripal and his daughter looks like revenge.

Tom Davies

Winchester

• Simon Jenkins, with his unfailing ability to sniff out hypocrisy wherever he sets his gaze, suggests that Russia is no more at war with Britain than Britain is with Syria. But it’s clear that, away from the public gaze, cyber- and other forms of hybrid warfare between Russia and the west are well advanced. With their constant harking back to the heroics of the great patriotic war 70 years ago (compare and contrast the derision directed by the 1960s generation at second world war vainglory), the Russian media and their sponsors in the Kremlin are slowly creating an adversarial mindset among the population at large. Not war as we have traditionally known it, perhaps, but potentially just as devastating.

Bernard Besserglik

Pantin, Paris, France

• Skripal would never have been targeted if the British government had reacted more forcefully when Alexander Litvinenko was killed, says a Russian defector (Brutal calling card brings terror to an ordinary city, 10 March); a delay attributable to Theresa May, when home secretary. So not only have we failed to harbour Afghan military translators, we can’t offer safe haven for spies who have served us. Worse is a hypocritical sense of outrage, as if only Russia were capable of such atrocities. Having admitted to a secret order, issued in August 2017, relating to crimes committed by MI5 (Report, 3 March), May is yet to come clean on what crimes British spies can commit. Can they torture? Blackmail? Threaten people’s families?

David Murray

Wallington, Surrey

• Lenin’s decision to set up the Scientific-Research Institute NII-2 (Deadly story of the KGB’s poisons factory, 10 March) was surely a response to Churchill’s use of the chemical weapon diphenylaminechloroarsine, dropped by British planes fighting the Bolsheviks in north Russia during the summer of 1919.

John Howlett

Rye, East Sussex

• This double agent in Salisbury was deported from Russia, presumably without funds. Does the government provide lifetime support to him and other spies? Please “follow the money” and tell us.

Steve Richards

Bath

• On 14 December I introduced a private members bill in the House of Lords to give clear powers to the government to refuse visas to people who abuse human rights. It was the other half of the Magnitsky Act – the government had already been forced to accept amendments to freeze the accounts of abusers of human rights.

(Sergei Magnitsky, a Russian lawyer, was acting for the banker Bill Browder when he was arrested, imprisoned and murdered in a Russian gaol; Browder has worked long and hard to see his killers and others like them brought to justice and to create legislative change in his lawyer’s memory.)

The government should be refusing visas to any people whose records on human rights are suspect. When the second reading of my bill took place, it had support from peers on all benches but was opposed by the government, claiming it already had sufficient powers. We have to ask why the government has been resisting Magnitsky legislation. It would be utterly shameful if this was linked to anxiety by any party of losing political donations or the desire to bring Russian money into the country.

Helena Kennedy QC

House of Lords

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