BOSTON — An Air National Guard member has pleaded guilty to posting dozens of classified documents online in one of highest-profile intelligence leaks in recent years.

Prosecutors recommend that Jack Teixeira, 22, be sentenced to up to 16 years and eight months in prison.

While working at an Air National Guard base, he posted documents to Discord, a platform popular with gamers.

The material included maps, satellite images and intelligence on US allies.

Teixeira pleaded guilty to six counts of willful retention and transmission of national defense information in a US federal court in Boston on Monday.

Each count carries a maximum sentence of 10 years in prison. However, under the details of a plea deal, prosecutors agreed to ask for a term of 200 months in prison — which Teixeira has agreed not to contest.

He will also be fined $50,000 (£39,000).

Teixeira initially began sharing classified information in late 2022 to a small community of gun and military enthusiasts on a Discord server, or chatroom.

Initially the documents stayed within the group — and Teixeira expressed frustration that his online friends did not realize their significance — but the information was soon re-shared to more public channels.

Eventually, the documents spread to fringe message boards and bigger social media networks, and were picked up by pro-Kremlin Telegram channels and military bloggers.

Some copies of the documents were later altered by others, for instance to inflate Ukrainian casualty figures.

Teixeira was based at the Otis Air National Guard Base, near his home a little more than an hour south of Boston, Massachusetts.

He worked as a cyber defense operations journeyman — an information technology job maintaining the Air Force communications network — and held the rank of Airman 1st Class. Despite his junior role, he had a top-secret security clearance.

The leak prompted an investigation and led the Pentagon to examine its systems for handling classified information.

The Air Force disciplined 15 of its members in connection with the case in December. A report said officers were aware Texiera's "intelligence-seeking activities" and failed to stop him.

Leaders in his unit were aware of up to four instances of "questionable activity" by Teixeira involving his access to classified material, the report by the Air Force Inspector General said.

Several officers knew of other incidents, the report said, but they did not report them through the proper channels, fearing that security officials would "overreact".

Teixeira was warned by his supervisors after he was seen making notes while looking at classified documents, prosecutors said, and posed specific questions based on classified intelligence during a briefing.

The report said there was a lack of supervision during overnight shifts at the base, when a three-person crew was responsible for answering phones and ensuring the heating and air conditioning systems were operating.

Teixeira took advantage of that lack of supervision to print off classified documents and smuggle them out of the base. Screenshots of the classified information appeared to showed creased printouts photographed at his home.

However, the Air Force Inspector General report noted that none of his supervisors knew the full extent of Teixeira's online activities.

In court filings, prosecutors said Teixeira was once suspended from high school after a classmate overheard him making racial threats and talking about weapons.

Teixeira claimed he was talking about a video game, but the incident led local police to deny him a firearms identification card which would allow him to purchase weapons.

He was eventually approved, however, and authorities found a number of guns when they searched his house after his arrest.

Prosecutors also said he attempted to destroy evidence, smashing his tablet, laptop and Xbox and encouraging members of the Discord chat room where he leaked files to delete their messages as authorities closed in.

Teixeira's family has a history of military service. His stepfather served 34 years in the Air Force, and his mother previously worked for non-profit organizations focused on veterans. Both attended his plea hearing on Monday. — BBC