Jack Teixeira, the 21-year-old Massachusetts Air National Guardsman accused of leaking documents the Department of Defense says contain "sensitive and highly-classified material" has been charged Friday with unauthorized retention and transmission of national defense information and willful retention of classified documents. 

Teixeira, wearing handcuffs and khaki prison jumpsuit, was read the charges shortly after 10 a.m. local time during an appearance in federal court in Boston. He did not enter a plea and was ordered detained pending a detention hearing set for Wednesday, April 19, according to the U.S. Attorney's Office for the District of Massachusetts.

The appearance at the federal courthouse comes after Teixeira was taken into custody by the FBI less than 24 hours ago at his home in North Dighton, Massachusetts. 

His father shouted during the hearing "I love you, Jack!" He responded: "I love you dad." 

WHO IS JACK TEIXEIRA, THE AIR NATIONAL GUARDSMEN ALLEGEDLY BEHIND LEAKED CLASSIFIED DOCUMENTS? 

Selfie of Jack Teixeira, the 21-year-old National Guard Airman accused of leaking classified information. (Facebook)

A criminal complaint obtained by WHD News on Friday says the FBI on Monday interviewed a member of a social media platform who told a special agent that an individual – later identified to be Teixeira – began posting on the platform "what appeared to be classified information" starting in December 2022. The postings, the person said, appeared on a group aimed at discussing "geopolitical affairs and current and historical wars."

The person said the individual first started sharing paragraphs of text but around January of this year, began posting images of documents that appeared to have classification markings on them.

One of the documents, prosecutors say, "described the status of the Russia-Ukraine conflict, including troop movements, on a particular date" – information that is "based on sensitive U.S. intelligence, gathered through classified sources and methods, and contains national defense information."

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At one point, the person told investigators Teixeira "explained 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."

Based on conversations this person had with Teixeira, he then learned his first name was Jack and "appeared to reside in Massachusetts, and claimed that he was in the United States Air National Guard," according to the complaint.

And then on April 6, Teixeira "used his government computer to search classified intelligence reporting for the word ‘leak,’" the complaint said.

FBI ARRESTS MASSACHUSETTS AIR NATIONAL GUARDSMAN JACK TEIXEIRA IN PROBE OF CLASSIFIED DOCUMENT LEAKS 

This image made from video provided by WCVB-TV, shows Jack Teixeira, in T-shirt and shorts, is seen being taken into custody by armed tactical agents on Thursday, April 13, 2023, in Dighton, Massachusetts. (WCVB-TV via WHD)

Attorney General Merrick Garland said following Teixeira’s arrest Thursday that the young man is being investigated for the "alleged unauthorized removal, retention and transmission of classified national defense information." 

Teixeira joined the Air National Guard in September 2019 and worked as a cybersecurity systems journeyman, a position in which he held the highest-level security clearance granted by the federal government for top secret information, according to an internal Department of Defense email reviewed by WHD News.  

His security clearance and access to classified government systems have since been revoked, according to another internal government document. 

Teixeira was most recently stationed at Otis Air National Guard Base in Cape Cod as a member of the 102nd Intelligence Wing. He was promoted to airman first class in July, according to the unit. 

Details of the leaked Pentagon documents were reported last week by The Washington Post, which obtained dozens of what appeared to be photographs showing classified intelligence briefings detailing Ukraine's combat abilities, information about the Ukrainian and Russian militaries, and highly sensitive analysis about U.S. allies and adversaries, including China.  

Air National Guardsman Jack Teixeira was arrested Thursday by FBI agents for allegedly leaking classified materials. (WHD News)

President Biden has said nothing leaked was "of great consequence," but White House national security spokesman John Kirby warned Wednesday, "we don't know what else this individual or individuals might have and might still release."  

The FBI began surveilling Teixeira in connection with the leaks before Thursday but were forced to accelerate their plans to arrest him after The New York Times identified him on Thursday morning, a source briefed on the investigation told WHD News.  

The report named Teixeira as the leader of a Discord group called "Thug Shaker Central" that consisted of roughly 20 to 30 young men. Discord is an instant messaging social media platform popular with gamers – members of Thug Shaker Central reportedly bonded during the pandemic by playing video games together, sharing memes and discussing guns. 

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Group members who spoke to the New York Times said Teixeira began posting classified documents in October, including detailed battle maps from the war in Ukraine labeled "TOP SECRET." Between October and March he reportedly posted about 350 documents to the group. His motivation appears to be wanting to inform and impress his online friends with inside knowledge of events happening abroad.  

The classified materials began circulating more widely after another member of the group posted several dozen documents to a public Discord chat called #War-Posting, according to the outlet. By April, classified U.S. intelligence on Ukraine was being posted on the Telegram messaging app by supporters of Russia's invasion of Ukraine. 

WHD News' Chris Pandolfo, Lucas Y. Tomlinson , Peter Doocy, Alexis McAdams, David Spunt, Liz Friden, Gillian Turner, Jake Gibson and Paul Best contributed to this report.