Hoffman, 40, of Virginia Beach, Va., was convicted last August of trying to spy for Russia. He served in the U.S. Navy for 20 years before retiring at the rank of Petty Officer First Class in 2011.
The former Navy cryptologic technician was arrested on Dec. 6, 2012, after an FBI sting operation to see if he was willing to spy against the United States, the U.S. Attorney's Office for the Eastern District of Virginia said Monday in a release.
As part of this investigation, undercover FBI agents posing as Russian operatives contacted Hoffman seeking defense information. In a series of emails and other communications, Hoffman advised that he looked forward to "renewing [a] friendship" with his purported Russian contact, was "willing to develop a mutual trust," and wanted to be compensated for his activities.
Prosecutors said Hoffman used a drop site to leave encrypted thumb drives containing answers to questions posed to him by U.S. investigators posing as Russian agents. The answers contained national defense information classified as secret or top secret.
"Hoffman attempted to spy on behalf of the Russian Federation and betrayed the trust this country placed in him. He was willing to place American lives at risk for personal gain," acting U.S. Attorney Dana Boente said in a statement. "Today's sentence should serve as a clear warning to others who would willingly compromise our nation's most sensitive classified information."