Russia's Supreme Court on Tuesday upheld the 25-year sentence handed down in absentia to Foreign Intelligence Service colonel Alexander Poteyev, who had betrayed a U.S. spy ring in 2010.
A Moscow military district court found 59-year-old Poteyev guilty of high treason in June.
Poteyev, who was recruited by the CIA in the 1990s, fled to the United States with his family shortly before the arrest of the sleeper agents was made public.
The Supreme Court's military board hearings were held in a closed session, as were those of the Moscow military district court.
The ten Russian nationals were arrested by U.S. law enforcement on June 27, 2010 on suspicion of being part of an espionage ring spying for Russia. They were quickly tried and flown out of the United States in an exchange for four people convicted of spying in Russia for the West.
Prime Minister Vladimir Putin, a 16-year veteran of the KGB service, said last year that "traitors" always "end up badly, taking to drink or drugs, or in a gutter."
However Putin refused to say whether Russia was planning to take revenge, saying secret services lived by their own laws and it was up to them to resolve these issues.