By Li Hongmei

A court in Norfolk, Virginia, on Monday passed a guilty verdict on Robert Hoffman II, a retired cipher officer of the US Navy, and sentenced him to 30 years in jail for an ostensible attempt of espionage for Russia.

Hoffman was initially facing a life sentence for an attempt to transfer secrets to FBI agents who passed themselves off for agents of Russian intelligence services.

Prosecution said Hoffman had allegedly handed some confidential data on US naval ships to them.

In September and October 2012, Robert Hoffman II, now 40, a 20-year veteran of the US Navy, turned over classified defense information to FBI agents he believed were Russian, according to Virginia prosecutors.

In the Navy, Hoffman was deployed on US submarines where he worked with electronic sensors to collect information on potential adversaries.

In that role, he was awarded security clearances and agreed not to disclose information to unauthorized persons, the statement said.

During the FBI operation, Hoffman asked the undercover agents he thought were his contacts for "compensation for his activities in the form of job assistance or payments based upon the risk and effort involved," it added.

On three separate occasions, he turned over "secret," "top-secret" and "sensitive" information saved on an encrypted USB memory stick, leaving it, per prior agreement, in a hole at the base of a tree.

He was arrested in December 2012, charged in the spring of 2013 and found guilty after a five day trial in August in Virginia.

His sentence was made public Monday.

"By attempting to hand over some of America's most closely held military secrets, Robert Hoffman put US service members and this country at risk," said John Carlin, Acting Assistant Attorney General for National Security.

Hoffman served at the US Navy for about twenty years and retired in November 2011. He was arrested in December 2012 and charges were issued to him six months later.