■Jack Teixeira pleads guilty to leaking Ukraine war documents and other secrets.

■The breach raised concerns over America’s ability to protect its classified data.

■Teixeira’s defense will argue that his youth played a role in his conduct.

BOSTON — Massachusetts Air National Guard member Jack Teixeira pleaded guilty on Monday to leaking highly classified military documents about the war in Ukraine and other national security secrets under a deal with prosecutors that calls for him to serve at least 11 years in prison.

Teixeira, of North Dighton, Massachusetts, pleaded guilty to six counts of willful retention and transmission of national defense information under the Espionage Act nearly a year after he was arrested in the most consequential national security leak in years.

The 22-year-old admitted illegally collecting some of the nation’s most sensitive secrets and sharing them with other users on Discord, a social media platform popular with people playing online games.

U.S. District Judge Indira Talwani scheduled sentencing for September in Boston’s federal court and said she would decide then whether to formally accept the agreement, which calls for a prison sentence between 11 and nearly 17 years. Prosecutors said they plan to seek the high end of that range.

“Mr. Teixeira callously disregarded the national security of the United States and he betrayed his solemn oath to defend the country and the trust of the American people he swore to protect,” Matt Olsen, assistant attorney general for national security, told reporters after the hearing.

Impact of the Security Breach

The stunning security breach raised alarm over America’s ability to protect its most closely guarded secrets and forced the Biden administration to scramble to try to contain diplomatic and military fallout. The leaks embarrassed the Pentagon, which tightened controls to safeguard classified information and disciplined members found to have intentionally failed to take required action about Teixeira’s suspicious behavior.

Teixeira smiled at his father before being led out of the courtroom with his hands and legs shackled, wearing orange jail garb and black rosary beads around his neck. He stood flanked by defense attorneys through much of the hearing and occasionally leaned down to speak into the microphone to answer questions from the judge.

Defense’s Perspective

Michael Bachrach, an attorney for Teixeira, told reporters they will push for a sentence of 11 years. Bachrach described Teixeira as a “kid,” adding that the defense will show at sentencing that his youth played a significant role in his conduct.

“He is significantly remorseful for his conduct. He has accepted full responsibility for his conduct,” Bachrach said.

In an emailed statement, Teixeira’s family said: “It is unfathomable to think your child would ever be involved in something so serious, but he has taken responsibility for his part in this, and here we are.”

“Our focus now remains on Jack – his protection, health, and well-being, and taking care of whatever is in his best interest,” they said.

Teixeira’s Role in the Air National Guard

Teixeira, who was part of the 102nd Intelligence Wing at Otis Air National Guard Base in Massachusetts, worked as a cyber transport systems specialist, essentially an information technology specialist responsible for military communications networks. He remains in the Air National Guard in an unpaid status, an Air Force official said.

Authorities said he first typed out classified documents he accessed and then began sharing photographs of files that bore SECRET and TOP SECRET markings. Prosecutors also said he tried to cover his tracks before his arrest, and authorities found a smashed tablet, laptop and Xbox gaming console in a dumpster at his house.

The leak exposed to the world unvarnished secret assessments of Russia’s war in Ukraine, including information about troop movements in Ukraine and the provision of supplies and equipment to Ukrainian troops. Teixeira also admitted posting information about a U.S. adversary’s plans to harm U.S. forces serving overseas.

Prosecution’s View

Acting Massachusetts U.S. Attorney Josh Levy told reporters Monday he would not speculate on Teixeira’s motive. But members of the Discord group described Teixeira as someone looking to show off, rather than being motivated by a desire to inform the public about U.S. military operations or to influence American policy.

In exchange for Teixeira’s guilty plea, prosecutors agreed not to charge him with further Espionage Act violations. As part of the deal, Teixeira must participate in a debrief with members of the intelligence community, the Defense Department and the Justice Department about the leaks.

Teixeira has been behind bars since his April arrest. The judge denied his request for release from jail last year after prosecutors revealed he had a history of violent rhetoric and warned that U.S. adversaries who might be interested in mining Teixeira for information could facilitate his escape.

Prosecutors have said Teixeira continued to leak government secrets even after he was warned by superiors about mishandling and improper viewing of classified information. In one instance, Teixeira was seen taking notes on intelligence information and putting them in his pocket.

The Air Force inspector general found that members “intentionally failed to report the full details” of Teixeira’s unauthorized intelligence-seeking because they thought security officials might overreact. For example, while Teixeira was confronted about the notes, there was no follow-up to ensure the notes had been shredded and the incident was not reported to security officers.

It was not until a January 2023 incident that the appropriate security officials were notified, but even then security officials were not briefed on the full scope of the violations.