By MICHAEL CASEY

BEDFORD, Mass. (AP) — A court-martial convened on Monday for Massachusetts Air National Guard member Jack Teixeira, who was sentenced in federal court last year to 15 years in prison for leaking highly classified military documents after the most consequential national security breach in years.

Teixeira pleaded guilty last year to six counts of willful retention and transmission of national defense information under the Espionage Act. He faces additional military charges of disobeying orders and obstructing justice in the court-martial, held at Hanscom Air Force Base in Massachusetts.

His lawyer argued for dismissal of the obstructing justice charge. Lt. Col. Bradley Poronsky said that it would amount to double jeopardy because it already came up at Teixeira’s November sentencing. Prosecutors disagreed.

The military judge took the matter under advisement and postponed the proceeding until Thursday.

Military prosecutors said the court-martial is appropriate given that obeying orders is the “absolute core” of the military. Teixeira’s lawyers argued that further action would amount to prosecuting him twice for the same offense.

The leaks 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.

Before he was sentenced in U.S. District Court in Boston, Teixeira showed little emotion as he stood in court and apologized for his actions. The 22-year-old previously admitted he illegally collected some of the nation’s most sensitive secrets and shared them with other users on the social media platform Discord.

“I wanted to say I’m sorry for all the harm that I brought and caused,” Teixeira said. “I understand all the responsibility and consequences fall upon my shoulders alone and accept whatever that will bring.”

Afterward, Teixeira hugged one of his attorneys, looked toward his family and smiled before being led from court. His family left without commenting to reporters, but his mother and others submitted letters to the court seeking leniency.

″I know Jack deeply regrets his actions and is ready to accept his punishment for his part in this situation,” his mother, Dawn Dufault, wrote. “While I understand the severity of his charges and the importance of ensuring justice, I implore you, Your Honor, to consider Jack’s true nature and his unique challenges, as I have observed over the years.”

The security breach raised alarm over the country’s ability to protect its most closely guarded secrets and forced the Biden administration to scramble to try to contain the diplomatic and military fallout. The leaks also 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, of North Dighton, Massachusetts, was part of the 102nd Intelligence Wing at Otis Air National Guard Base in Massachusetts. He worked as a cyber transport systems specialist, which is 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.

Teixeira’s lawyers described him as an autistic, isolated individual who spent most of his time online, especially with his Discord community, and never meant to harm the United States. “His intent was to educate his friends about world events to make certain they were not misled by misinformation,” they wrote. “He needed someone to share the experience with.”

Prosecutors countered that Teixeira did not suffer from any intellectual disability and that his post-arrest diagnosis of “mild, high-functioning” autism was of “questionable relevance.”

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. Authorities found a smashed tablet, laptop and an Xbox gaming console in a dumpster at his house.