Jack Teixeira, 21, makes second court appearance, as his lawyers ask for more time before hearing on his detention.

Jack Teixeira, 21, made a brief appearance in federal court in Boston on Wednesday and waived his right to a preliminary hearing – an early court proceeding in which prosecutors present some evidence to show that charges are warranted.

His defence had said it “requires more time to address the issues presented by the government’s request for detention”.

A judge had ordered Teixeira last week to remain in custody until a detention hearing is held. Teixeira has not entered a plea of guilty or not guilty. Suspects are usually allowed to remain free on bail until trial, unless prosecutors convince the judge that a defendant may flee or poses a risk to the community.

Teixeira was brought to the courtroom in handcuffs and orange jail garb. He only responded with “yes” and “no” to questions about whether he understood his rights and the proceeding.

Teixeira was arrested in the small town of Dighton, Massachusetts last week and charged under the Espionage Act with the unauthorised removal, retention and transmission of classified national defence information.

The files that Teixeira allegedly leaked have been described by experts and officials as a threat to national security.

They included details of Western military support to Ukraine, information about Russia’s war effort and intelligence collected from allied states.

Officials have said Teixeira, who served in the Massachusetts Air Force National Guard, shared the information with members of a Discord server to “discuss geopolitical affairs and current and historical wars”.

An FBI court document said last week that the social media user was posting paragraphs of text that showed what “appeared to be classified information” around December 2022. The user then started publishing photos of the purported documents around January.

The poster, believed to be Teixeira, told a witness that he “had become concerned that he may be discovered making the transcriptions of text in the workplace, so he began taking the documents to his residence and photographing them”, the FBI affidavit reads.

Teixeira’s age and junior rank have raised questions about why he had access to top-secret information and how he was able to leak the documents over several weeks without being detected. Many Congress members have pledged to seek answers about the issue.

The US Air Force announced on Tuesday that it was halting the intelligence mission of Teixeira’s unit, the 102nd Intelligence Wing, as an inspector general carries out an investigation into the leaks.

“The 102nd Intelligence Wing is not currently performing its assigned intelligence mission,” Air Force Spokesperson Ann Stefanek said in a statement.

The Air Force inspector general would investigate the unit’s “compliance with policy, procedures, and standards … related to the release of national security information,” Stefanek added.

As Teixeira’s legal case proceeds, details from the leaked document have continued to trickle down through US media outlets.

On Wednesday, the Washington Post reported – based on the leaked documents – that China was working on a high-altitude spy drone that could travel “at least three times the speed of sound”, which would boost Beijing’s surveillance capabilities in the Indo-Pacific.

US officials have not denied the validity of the documents, acknowledging that they “present a very serious risk to national security” and appear to be real, though in some cases altered.