Jack Teixeira, the man suspected of leaking highly-classified US documents online, is due to appear in court after his arrest on Thursday.
Teixeira, a 21-year-old National Guardsman from rural Massachusetts, is accused of being responsible for leaking secret documents about the Ukraine war and other national security issues.
He was arrested by the FBI at his home in Dighton, with footage showing him wearing shorts and a T-shirt as he was taken into custody. He will have an initial court appearance in Massachusetts on Friday.
US Attorney General Merrick Garland said he is to be charged with removing or transmitting classified national defence information, a crime under the Espionage Act.
Teixeira oversaw an online chat group made up of around 20-30 young men.
He is suspected of posting photographs of secret and top-secret documents into the group from late last year to March.
Former members of the group, dubbed Thug Shaker Central, have told media outlets including the New York Times and Washington Post that the documents appeared to have been shared in an attempt to impress the rest of the group.
The material was then posted outside the chat room group and became public knowledge, sparking embarrassment for the Biden administration and a massive hunt for the culprit.
Teixeira joined the National Guard in 2019, according to reports, and held the relatively junior position of “cyber transport systems specialist”.
The Pentagon said it would review its policies on safeguarding classified material, including assessing who should be on its distribution lists.
Pentagon spokesman Brigadier General Patrick Ryder said: “We do have strict protocols in place, so any time there is an incident there’s an opportunity to review that and refine it.”
Although defence officials have voiced alarm at the leak, the Biden administration has also scrambled to contain the potential diplomatic fallout from the leaks.
Mr Biden has downplayed the long-term impact of the disclosures, telling reporters in Ireland earlier Thursday that “there’s nothing contemporaneous that I’m aware of that is of great consequence.”
However, the chair of the British Commons defence select committee has warned the leak which includes information about UK special forces could “endanger lives”.
The Ministry of Defence warned against taking allegations contained in the reported leak at “face value”.
But committee chair Tobias Ellwood told The Times: “Given our long-established lead in scale and capability when it comes to elite forces, it will come as no surprise that our special forces are doing much of the heavy lifting.
“But this deliberate, large-scale disclosure of sensitive material could easily endanger lives and should prompt an urgent review about who has access to sensitive information and how it is shared.”
It has been reported the document, dated March 23, indicates as many as 50 UK special forces personnel have been deployed to the country alongside other western special forces.
The leak is believed to have started on Discord, a social media platform popular with gamers, where Teixeira is believed to have posted for years.
The investigative website Bellingcat and The New York Times first publicly identified Teixeira, minutes before federal officials confirmed he was a subject of interest in the investigation.
They reported tracking profiles on other more obscure sites linked to Teixeira.
