Jack Teixeira, 21, of the Massachusetts Air National Guard, was charged with “unauthorized retention and transmission of national defense information,” according to CNN, citing court documents.
The young military man was also accused of “unauthorized removal and retention of documents or classified materials”.
Teixeira was not obliged to make any statement about his possible culpability.
The defendant simply responded calmly when the judge advised him on his rights, according to the Spanish agency EFE.
At one point during the hearing, a man shouted “I love you, Jack” from the back of the courtroom, to which the suspect responded without turning around: “I love you too, Dad”, added EFE.
A federal magistrate ordered him to remain in custody until at least the arrest hearing, scheduled for next Wednesday, April 19.
Jack Teixeira, a native of Swansea, Massachusetts, was arrested on Thursday.
The FBI (US federal police) arrested Teixeira because the clues pointed him as responsible for a leak of secret documents in the United States.
Billing records from an Internet media platform helped the FBI identify the suspect, according to court records consulted by the US agency AP.
Teixeira started posting the documents in a Discord chat room, but his reach exploded in March, when a user spread the documents to other groups with more members.
The files detail the US assessment of the war in Ukraine and data on the status of Russian forces, as well as sensitive material on Canada, China, Israel and South Korea.