WASHINGTON (Reuters) - A former employee of the U.S. National Security Agency (NSA) was sentenced on Monday to nearly 22 years in prison for attempting to transmit classified information to someone he thought to be a Russian agent but turned out to be an FBI undercover employee, the U.S. Justice Department said.

Jareh Sebastian Dalke, 32, of Colorado Springs, Colorado, pleaded guilty in October to six counts of attempting to transmit classified national defense information. He was sentenced on Monday to 21 years and 10 months in prison.

"This sentence should serve as a stark warning to all those entrusted with protecting national defense information that there are consequences to betraying that trust," FBI Director Christopher Wray said in a statement.

Dalke admitted that between August and September 2022, in order to demonstrate both his "legitimate access and willingness to share," he used an encrypted email account to transmit excerpts of three classified documents to an individual he believed to be a Russian agent, the Justice Department said.

Dalke, who worked at NSA as an information systems security designer, asked for $85,000 in return for all the information in his possession, the department said.

(Reporting by Eric Beech; Editing by Sandra Maler)