(NewsNation) — Jack Teixeira, a 21-year-old National Guard member, has been arraigned on two charges of leaking classified documents.

Teixeira was charged with unauthorized detention and transmission of national defense information and unauthorized removal of classified information and defense materials. He did not enter a plea and has been detained, with a detention hearing set for Wednesday.

President Joe Biden on Friday commended the “rapid action taken by law enforcement.”

“While we are still determining the validity of those documents, I have directed our military and intelligence community to take steps to further secure and limit distribution of sensitive information, and our national security team is closely coordinating with our partners and allies,” the statement read in part.

Court documents show the FBI used Discord billing records to identify Teixeira. Discord, a chat server popular with gamers, was where sources say Teixeira first shared the documents in a private group. In the court documents, investigators disclosed that Teixeira began photographing documents after expressing concern to other group members that he might be discovered transcribing the text at work.

In addition, court documents say Teixeira used his government-provided computer to search for the word “leak” in classified materials, giving investigators reason to believe he was looking for information on what the intelligence community knew about the leaker.

Teixeira was arrested Thursday following a Department of Justice investigation into who was behind the release of photographs of classified materials that circulated on social media sites. The Massachusetts Air National Guard member specialized in intelligence. Teixeira was taken into custody without incident.

The documents revealed information on the war in Ukraine, including the dire state of Ukraine’s air defense. Other national security information in the documents included information on the Middle East and China, and details on U.S. intelligence operations in Russia. The documents also indicated the U.S. is spying on allies like South Korea and Israel.

Lawmakers immediately pressed the Pentagon on how such sensitive information could be leaked. The photographs of the documents show crease lines from being folded, a suspected result of the leaker pocketing the materials to later share.

The photographs of the material were first posted on a private Discord server. The Associated Press stories say the leaker was identified as “the O.G.” by a member of the online chat group. Known as Thug Shaker Central, the group drew roughly two dozen enthusiasts who talked about their favorite types of guns and also shared memes and jokes, some of them racist. The group also held a running discussion of wars that included talk of Russia’s invasion of Ukraine.

In that discussion, “the O.G.” would for months post material that he said was classified — originally typing it out with his own notations, then a few months ago switching to posting images of folded-up papers because he felt his writings weren’t being taken seriously, said the group member, who declined to share his name with AP.

It was not immediately clear how Teixeira would have had access to the records, but a Defense Department official told The Associated Press on Thursday that as an IT specialist responsible for military communications networks, the young National Guard member would have had a higher level of security clearance.

Teixeira reportedly shared classified information on the Discord server for years before the documents were circulated on other social media sites, including Twitter.

Sultan Meghji, a cybertechnology expert and professor at Duke University, says the U.S. government can bolster its security protocols by upgrading outdated and insufficient technology systems.

“It doesn’t understand the new rules around top secret and SCI, it doesn’t understand how to compartmentalize information better,” Meghji said of the current tech software. “This isn’t a world of file folders and file cabinets and folders with red tape on it. It all, to a degree, looks like a Google search or looks like what you would have on your normal computer except a slightly different system, and those systems have to be radically updated.”

The Associated Press contributed to this report.