Jack Teixeira appeared in federal court in Boston following a week-long probe into one of the most damaging leaks of secrets since the 2013 dump of National Security Agency documents by Edward Snowden.
His dramatic arrest Thursday followed a week-long investigation into one of the most damaging leaks of classified information since the 2013 dump of National Security Agency documents by Edward Snowden.
Teixeira's arrest came a day after The Washington Post reported that hundreds of pages of documents had been posted on the social media platform Discord by a man who worked on a US military base.
According to The New York Times, a "trail of digital evidence" pointed to Teixeira as the leader of the private group on Discord, called Thug Shaker Central, where the documents surfaced.
US Attorney General Merrick Garland said Friday there were "very serious penalties" associated with the leaking of scores of classified defense documents after a national guardsman was charged in the case.
"People who sign agreements to be able to receive classified documents acknowledge the importance to the national security of not disclosing those documents, and we intend to send that message how important it is to our national security," he added.
The US National Guard Bureau said Teixeira had enlisted in September 2019 and was an IT and communications specialist who reached the rank of airman first class - the third-lowest for enlisted air force personnel.
US Defense Secretary Lloyd Austin said he was ordering a "review of our intelligence access, accountability and control procedures within the (Defense) Department to inform our efforts to prevent this kind of incident from happening again."
The embarrassing security breach has revealed US unease over the viability of a coming counteroffensive by Kyiv's forces against Russian troops as well as concerns about Ukrainian air defenses, and pointed to US spying on allies including Israel and South Korea.
US media reported that the Biden administration is seeking to beef up its monitoring of social media sites and chat rooms after intelligence agencies failed to spot the leaked documents online for weeks.
The Pentagon has also "begun to limit who across the government receives its highly classified daily intelligence briefs," CNN reported on Thursday.