LONDON (AP) — A former security guard at the British Embassy in Berlin was sentenced Friday to more than 13 years in prison for putting U.K. diplomats at “maximum risk” by selling secret information to Russia.

David Ballantyne Smith admitted spying but claimed he was driven by depression and a desire to “teach the embassy a lesson” because he felt badly treated at work.

But Judge Mark Wall said Smith was motivated by hatred of the U.K. and support for Russian President Vladimir Putin.

“He was paid for his treachery, and he was motivated by his antipathy towards this country and intended to damage this country’s interests by acting as he did,” Wall said.

Passing sentence at London’s Central Criminal Court, the judge said Smith’s actions had “potentially catastrophic consequences for others.”

He sentenced Smith to 13 years and two months in prison for eight breaches of the Official Secrets Act.

Smith, 58, gave the Russian Embassy in Germany’s capital information about the activities, identities, addresses and phone numbers of British officials, prosecutors said. Smith also collected intelligence on the operation and layout of the British Embassy, which prosecutors said would be useful to “an enemy, namely the Russian state.”

The judge said Smith sent the Russians photographs of U.K. embassy staff with annotated descriptions that put them at “maximum risk.”

Prosecutors say the former Royal Air Force member had expressed sympathy with Russian authorities and consumed online conspiracy theories and pro-Russia propaganda. They said Smith had inside his locker at work a cartoon of Putin with his hands around former German Chancellor Angela Merkel in Nazi uniform – reflecting the sort of false narrative Russia has used to justify its invasion of Ukraine.

German police arrested Smith at his home near Berlin in August 2021 after a sting operation conducted with British intelligence officers that included undercover operatives posing as a Russian defector and a Russian spy. He was extradited to the U.K. in April 2022.

Nick Price of the Crown Prosecution Service said Smith had “abused his position in the British Embassy in Berlin” to carry out “an attack on our country.”

“His actions were not just driven by money and greed,” Price said. “On multiple occasions, he expressed a strong dislike towards the U.K. and Germany and expressed sympathy with the Russian authorities. These beliefs may have caused further damage had Smith not been discovered and prosecuted.”

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