Edward Devenney, 30, pleaded guilty on Tuesday to collecting secret coding programs used by the British and attempting to pass the classified information on to Moscow.
Devenney, who is formerly from Northern Ireland, was a submariner on HMS Vigilant, a Trident nuclear submarine, when he decided to pass on secrets to the “enemy”, it is understood. The submarine – one of four that make up the UK’s nuclear deterrent – is normally based at Faslane in Scotland but had been refuelling at Devonport dock in Plymouth when Devenney’s activities raised the suspicions of his senior officers.
Devenney’s motivation, it is believed, was unhappiness with his situation and a degree of anger towards his employers after being passed over for promotion, rather than an issue of ideology or money.
A prolific tweeter, his behaviour raised the suspicions of his senior officers and over a period of months an undercover operation was carried out.
This led to Devenney contacting two people he believed were from the Russian secret service and discussing information relating to the movement of nuclear submarines with them. However, he was in fact talking to British agents.
Devenney was arrested and charged under the Official Secrets Act. He appeared at the Old Bailey in London and pleaded guilty to gathering details of encryption programs in breach of the act.
The charge related to collecting information for a purpose prejudicial to the safety of the state between 18 November 2011 and 7 March 2012. The information was described in court as “crypto material” – or codes used to encrypt secret information – which could be useful to an enemy.
Devenney also admitted a charge of misconduct in a public office in relation to a meeting with two people he believed were from the Russian secret service. He admitted meeting the two individuals and discussing the movement of nuclear submarines with them. He denied a further count of communicating information to another person. The Crown Prosecution Service would not pursue this charge, the court heard.
HMS Vigilant’s £300m refit at Devonport involved upgrading the reactor core in a refuelling which will last the submarine the rest of its life. The refit was completed earlier this year and the submarine was returned to Faslane from where it has been taking part in extensive sea trials.
Devenney’s career on board the submarine is likely to be over, however. He is expected to be discharged from the navy if he is given a custodial sentence at the central criminal court in London next month. Parts of the prosecution case will be heard in secret.
Mr Justice Saunders told Devenney: “Your sentence will be adjourned to December 12 when I will hear all the matters and consider them all. Until then you are remanded in custody.”