A US sailor was sentenced to three years in prison after admitting he planned to give classified information about the US Navy’s nuclear-powered warships to a journalist then defect to Russia, officials said.

Stephen Kellogg III pleaded guilty to two counts of espionage on Friday. The 26-year-old had contacted Sevmash – Russia’s largest shipbuilding enterprise and only nuclear submarine producer, according to Navy court documents.

He wished to publish an expose on waste within the military and admitted he wanted to share the information with Russians, according to Jeff Houston of the Naval Criminal Investigative Service.

The former US Navy Petty Officer 2nd Class also admitted he knew releasing the information could degrade the ability of nuclear-powered warships, and therefore harm the US.

Authorities learned of his plans after arresting Kellogg on 27 August for drunken disorderly conduct at San Diego airport, where he was stopped by a Delta Air Lines employee from boarding a flight because he was being belligerent.

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He had bought a one-way ticket to New York City, where he planned to meet a journalist friend from high school after telling him he had a “big story” to reveal.

Kellogg had admitted to telling his roommate that he planned to defect to Russia and had searched online for flights to Moscow, contact information for the Russian Consulate in San Diego, and wrote to an email address associated with Sevmash and called the company six times. It is unclear if the Russian shipbuilder wrote back.

Around the same time, he told a childhood friend that he wanted to get out of the Navy and that I “might go Ed Snowden”, referring to the former National Security Agency contractor who exposed US government surveillance efforts by disclosing classified material.

USS Carl Vinson docked in Vietnam. Stephen Kellogg served on board between 2016 to 2018 (AP)

FBI special agent Garrett Waugh said: “This sailor’s attempts to disclose classified Navy nuclear propulsion information posed a significant threat to national security and endangered the lives of American service members.”

Though Kellogg pleaded guilty to two counts of violating the Espionage Act, his military defence attorneys told the judge at Naval Base San Diego before his sentencing that he was not a spy but rather had a drinking problem and may have been suffering from depression.

People who know Kellogg, they said, described him as harmless and someone just trying to get attention. The defence also pointed out that Kellogg had left his passport at his San Diego apartment, undermining claims he was headed to Russia.

Kellogg served on board the USS Carl Vinson between 2016 to 2018, having joined the Navy in 2014. The authorities said he admitted to photographing areas containing sensitive information about the nuclear propulsion program on the ship, and then sending the photos to his father and ex-girlfriend.

He told authorities he stored classified information in his berth, violating protocol, according to the FBI. He will receive a dishonourable discharge. “This type of behaviour has no place in our military,” said Commander Nate Christensen, deputy spokesman of the US Pacific Fleet.