The Massachusetts Air National Guardsman, Jack Teixeira arrested by the Federal Bureau of Investigation (FBI) over Pentagon leaks has been charged with unauthorised retention and transmission of national defence information.

Attorney General Merrick Garland announced Teixeira’s arrest by the FBI on Thursday afternoon, but the 21-year-old suspect made his first appearance in federal court in Boston on Friday in connection to the disclosure of dozens of secret documents that exposed sensitive intelligence and defence information, according to CBS.

An affidavit filed in court with the criminal complaint stated, “There is probable cause to believe that Teixeira improperly and unlawfully retained and transmitted national defence information classified at the TS/SCI level to persons not authorized to receive such information.”

It alleged that Teixeira, who held a top security clearance and sensitive compartmented access, received the sensitive government documents that were ultimately reposted on the internet in February 2023, according to logs kept by the federal government.

The report exposed that about a day later, according to charging documents, an online user reposted that information on the internet.

Federal investigators interviewed that user, identified in documents only as “User 1,” who told the FBI that the information was originally posted by an individual using Teixeira’s user name.

According to “User 1,” an individual utilizing Teixeira’s user name initially posted sensitive information as “paragraphs of text,” the criminal complaint explains, and around January 2023 began posting documents that appeared to contain classification markings.

Charging documents reveal that one of the posted documents “described the status of the Russia-Ukraine conflict, including troop movements, on a particular date.” The government confirmed that the document in question is classified at the highest level, according to the complaint.

Months later, on April 6 — the day media reports first surfaced about the leaked documents — investigators alleged Teixeira used his government computer to search classified intelligence reporting for the word “leak.”

“There is reason to believe that TEIXEIRA was searching for classified reporting regarding the U.S. Intelligence Community’s assessment of the identity of the individual who transmitted classified national defence information, to include the Government Document,” investigators alleged in court papers filed Friday.

According to CBS, Teixeira will be represented by a court-appointed attorney. If convicted, the 21-year-old faces up to 15 years in prison.

During his arraignment hearing, Teixeira responded “yes” when asked if he understood his right to remain silent. As the hearing ended, he was placed in handcuffs. As he was led away, a male family member seated in the court said, “Love you, Jack.”

A news helicopter flying over the suspect’s mother’s home in North Dighton, Massachusetts, captured footage Thursday afternoon of a man who appeared to be Teixeira walking backwards with his hands on his head as officers carrying rifles looked on.

According to Pentagon records, Teixeira joined the Air National Guard in 2019 and worked as a “cyber transport systems journeyman.”