A former officer in the US Army's elite Special Forces unit the Green Berets was sentenced to 15 and a half years in prison on Friday for spying for Russia.
Peter Rafael Dzibinski Debbins, 46, pleaded guilty in November to providing national security information to Russian intelligence operatives.
Debbins was sentenced to 188 months in prison on Friday by US District Court Judge Claude Hilton of the Eastern District of Virginia.
"Today's almost 16-year sentence reflects the seriousness of his conduct," Assistant Attorney General John Demers said in a statement.
"Debbins violated his oath as a US Army officer, betrayed the Special Forces, and endangered our country's national security."
According to prosecutors, the US-born Debbins was recruited by the Russians as early as 1996, before he had joined the army but after several trips to Russia, the native country of his mother.
"In 1997, Debbins was assigned a code name by Russian intelligence agents and signed a statement attesting that he wanted to serve Russia," the Justice Department said.
Debbins served in US Army chemical units from 1998 to 2005 before joining the Special Forces.
According to the Justice Department, Russian intelligence agents encouraged him to pursue a career in the Special Forces, where he reached the rank of captain.
"Over the course of the conspiracy, Debbins provided the Russian intelligence agents with... information about his chemical and Special Forces units," the department said.
"In 2008, after leaving active duty service, Debbins disclosed to the Russian intelligence agents classified information about his previous activities while deployed with the Special Forces," it said.
"Debbins also provided the Russian intelligence agents with the names of, and information about, a number of his former Special Forces team members so that the agents could evaluate whether to approach the team members to see if they would cooperate with the Russian intelligence service."
According to prosecutors, Debbins was based in Germany and later Azerbaijan with a high-level security clearance.
The last contact with his Russian handlers mentioned in his indictment was in 2011.
That year, according to his LinkedIn profile, Debbins began working for Washington-area defense and intelligence contractors and studying at a graduate school which focuses on national security and intelligence.