Jack Teixeira to appear in court accused of Pentagon leaks

The 21-year-old suspect in the recent leaks of Pentagon intelligence is due to appear in court on Friday.

Jack Teixeira was detained at his home by FBI agents, the US attorney general Merrick Garland announced on Thursday. The arrest was made “in connection with an investigation into an alleged unauthorised removal, retention and transmission of classified national defence information”, he said.

Helicopter news footage showed a young man with shorn dark hair, an olive-green T-shirt and red shorts being made to walk backwards towards a team of FBI agents, who were pointing their rifles at him, in the town of North Dighton, Massachusetts.

The Pentagon spokesperson, Patrick Ryder, said the leak of classified information was a “deliberate, criminal act”. He added that the Pentagon had taken measures to review distribution lists and make sure individuals who received information had a need to know.

The leak is believed to have started on Discord, a social media platform popular with people playing online games and where Teixeira is believed to have posted for years about guns, games and racist memes.

The investigative website Bellingcat and The New York Times 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.

Teixeira was a “cyber transport systems specialist”, essentially an IT specialist responsible for military communications networks, including their cabling and hubs. A defence official has told the Associated Press that in that role Teixeira would have had a higher level of security clearance, because he would have also been tasked with ensuring protection for the networks.

Speaking in Ireland on Thursday, Joe Biden sought to play down the impact of the breach. “I’m not concerned about the leak,” he said. “I’m concerned that it happened. But there’s nothing contemporaneous that I’m aware of that’s of great consequence.”

The Guardian has seen about 50 of the documents. But there are signs that many more were first posted on Thug Shaker Central. The New York Times said it had seen about 300 of the documents, only a fraction of which have so far been reported, indicating the national security damage could be worse than has so far been acknowledged.

One of the ways the leak could have an impact on US security is if it makes allies wary of sharing intelligence. The Polish prime minister, Mateusz Morawiecki, denied it would affect his country’s confidence in Washington’s ability to keep secrets.

“I’m not going to think twice,” Morawiecki told the Guardian at an Atlantic Council event in Washington. “I believe failures happen and mistakes happen, but we have to be as close as possible to our allies in western Europe and the United States. We have to unite on this front as well.”

Part of the inquest into the leak will examine how a 21-year-old air national guardsman in Massachusetts could have had access to top-secret material vital to US and allied security interests, including battlefield deployments in Ukraine. The Pentagon said it was reviewing its policies on safeguarding classified material, including updating distribution lists and assessing how and where intelligence is shared.

“It’s important to understand that this is not just about DoD [the defence department]. This is about the US government,” Ryder said. “This is about how we protect and safeguard classified information. We do have strict protocols in place, so any time there is an incident there’s an opportunity to review that and refine it.”