Jack Teixeira, 21, appeared briefly in federal court in Boston to waive his right to a preliminary hearing.

"Yes, your honor," Teixeira, wearing an orange jumpsuit, told the judge when asked if it was his decision to forego the hearing.

A separate appearance was delayed after his lawyer said the defense "requires more time to address the issues presented by the government's request for detention."

A new date has not yet been set but the defense requested a delay of a fortnight.

Teixeira, an IT specialist with the US Air Force National Guard, is accused of orchestrating the most damaging leak of US classified documents in a decade.

The documents unveiled US concern over Ukraine's ability to fend off the Russian invasion, and showed Washington has spied on allies Israel and South Korea.

He was arrested and charged on two counts last week following a week-long probe into the leak.

Teixeira is accused of the "unauthorized retention and transmission of national defense information" and the "unauthorized removal and retention of classified documents or material."

The counts carry maximum prison sentences of 10 years and five years, respectively.

He has not yet entered a plea.

Teixeira is suspected of posting the documents, some dated as recently as early March, to a private chat group on the social media platform Discord.

Some of the documents later appeared on other sites, including Twitter, 4Chan and Telegram.

Teixeira -- an airman first class, the third-lowest rank for enlisted air force personnel -- has possessed top secret security clearance since 2021.

The Pentagon has ordered a review into its control procedures following the leak.