A Russian court convicted US citizen Edmond Pope (54) to 20 years in prison on espionage charges. It was the first verdict against an alleged Western spy since the end of the Cold War.
The case has strained US-Russian ties. The verdict was described in Washington as "deeply disappointing".
The verdict, after a closed trial, was the worst possible for Pope, a businessman and former US Navy intelligence officer who consistently denied charges of trying to obtain secret information on a Russian torpedo.
As the sentence was read, Pope's wife Cheri - who was allowed into the courtroom for the first time only for the verdict - hugged him through the bars of the metal cage where defendants sit in Russian courts.
"Guilty, 20 years" was how the verdict was tersely announced by state prosecutor Mr Yuri Volgin as he left the courtroom after the sentence was read.
Defence lawyer Mr Pavel Astakhov denounced the trial as unfair, and a US Congressman warned darkly of punitive US steps.
Added to the fear of serving 20 years in a Russian jail, Pope's wife and his supporters have said the American's life is in danger from a rare form of bone cancer from which he is in remission.
Ms Pope has said she would plead with President Putin, a former KGB spy in the Soviet era, for a pardon.
President Clinton has also appealed to Putin to have Pope released but the Russian leader has said the court procedure must be finished first.