A U.K. court sentences a former Berlin embassy worker to 13 years in prison for spying for Russia.

A British court on Friday sentenced a former security guard at Britain’s embassy in Berlin to more than 13 years in prison for spying for Russia, in a case that has marred British efforts to present a united front in Ukraine’s fight against President Vladimir V. Putin’s invasion.

The former guard, David Ballantyne Smith, 58, whose intelligence gathering activities spanned four years, according to the judge in the case, had pleaded guilty to eight charges under Britain’s Official Secrets Act, but said that he had been depressed, lonely and drinking heavily at the time. He told the court that he had been motivated only by a desire to cause embarrassment to the embassy and had not intended to cause harm.

The judge, Mark Wall, dismissed those assertions during the sentencing on Friday, stating that Mr. Smith had developed “anti-British and anti-Western feelings” and that he had been motivated by financial reward, sympathies toward Russia and a desire to “damage British interests.” He added that Mr. Smith’s actions had placed the embassy’s staff “at maximum risk.”

The police in Germany arrested Mr. Smith in August 2021 after an undercover operation in which investigators posing as Russian agents approached him and offered him what they described as a chance to obtain highly sensitive information. That inquiry had begun a year earlier after a letter sent to a military staff member at the Russian Embassy in Berlin was traced back to Mr. Smith, suggesting that there had been prior contact between the two.

His intelligence gathering activities, which the judge said began in 2018, were laid bare in court.

The judge said that Mr. Smith had visited offices in the British Embassy at night, after employees had left, to take pictures of documents that the judge described as “secret.” The files, which the judge described as a “significant amount of material,” included a report addressed to then Prime Minister Boris Johnson by members of his cabinet, as well as documents revealing the names, photographs and personal details of embassy employees.

As part of the undercover operation, cameras inside the embassy’s security kiosk also captured Mr. Smith filming the embassy’s CCTV system. “This’ll do — I’ll get the rest tomorrow,” he was filmed saying to himself on one occasion.

Nick Price, the head of the Crown Prosecution Service’s special crime and counterterrorism division, said in a statement one day before the sentencing that Mr. Smith had “abused his position in the British Embassy in Berlin to covertly collect and pass sensitive information to the Russian state.”

“These crimes were an attack on our country and could have threatened national security,” Mr. Price said.