The Russia connectionRussia tested using door handles to deliver nerve agent before its agents attacked Skripal

The U.K. on Friday released previously classified intelligence that show that Russia had tested whether door handles could be used to deliver nerve agents and had targeted the email accounts of Sergei and Yulia Skripal since at least 2013.

The door handle and email claims were made in a letter from Sir Mark Sedwill, the U.K.’s national security adviser, to NATO secretary general, Jens Stoltenberg.

It is highly unusual for the U.K. to make such intelligence public, but the U.K. government appears to have concluded that such a move was necessary to counter the effective lies-and-disinformation campaign Russia has been conducting in an effort to deny its operatives has poisoned Skripel and his daughter. The Russian disinformation campaign has found some support in far-right and far-left circles in the U.K.

The Evening Standard reports that in the letter, Sedwill, who has an overview of the work of all British spy services, filled in some of the intelligence that Prime Minister Theresa May referred to when she made a House of Commons statement saying Russia was highly likely to have been behind the attack.

Sedwill said the nerve agent novichok had been developed at the Russian research facility in Shikhany as part of an offensive chemical weapons program with the codename Foliant.

Sedwill said Russia regarded at least some of its defectors as “legitimate targets for assassination,” with the suggestion that they could include Skripal, a former member of the GRU, Russian military intelligence, who was convicted by Russia of espionage in 2004 after working for MI6.

“We have information indicating Russian intelligence service interest in the Skripals, dating back at least as far as 2013, when email accounts belonging to Yulia Skripal were targeted by GRU cyber specialists,” Sedwill wrote.

He also said: “During the 2000s, Russia commenced a program to test means of delivering chemical warfare agents and to train personnel from special units in the use of these weapons. This program subsequently included investigation of ways of delivering nerve agents, including by application to door handles. Within the last decade, Russia has produced and stockpiled small quantities of novichoks under the same program.”

He said Russia had continued developing small amounts of novichok over the past decade.

“Russia’s chemical weapons program continued after the collapse of the Soviet Union. By 1993, when Russia signed the chemical weapons convention (CWC), it is likely that some novichoks had passed acceptance testing, allowing their use by the Russian military,” he said.

“Russia’s CWC declaration failed to report any work on novichoks. Russia further developed some novichoks after ratifying the convention. In the mid-2000s, President [Vladimir] Putin was closely involved in the Russian chemical weapons program. It is highly unlikely that any former Soviet republic (other than Russia) pursued an offensive chemical weapons program after independence. It is unlikely that novichoks could be made and deployed by non-state actors (e.g., a criminal or terrorist group).”

The Guardian reports that the Organization for the Prohibition of Chemical Weapons (OPCW), which is the UN chemical weapons watch dog, confirmed on Thursday that a novichok nerve agent had been used in the Salisbury attack.

Sedwill wrote: “I would like to share with you and allies further information regarding our assessment that it is highly likely that the Russian state was responsible for the Salisbury attack. Only Russia has the technical means, operational experience and the motive.”

Experts note that the term “highly likely” is one commonly used by the intelligence agencies when they believe something is 100 percent certain – but they still use “highly likely” since they are not willing to express that opinion without a caveat in case of error.

“Russia has a proven record of conducting state-sponsored assassination,” Sedwill said, concluding: “There is no plausible alternative explanation.”