A US federal judge sentenced 22-year-old Jack Teixeira, a Massachusetts Air National Guard member, to 15 years in prison on Tuesday for leaking a trove of classified Pentagon documents.

Authorities said Teixeira first typed out classified documents he accessed, and then began sharing photos of files marked as "Secret" and "Top Secret," before trying to cover his steps by throwing his electronic devices into the dumpster next to his house.

Wearing an orange jumpsuit when brought into court, Teixeira showed no visible reaction as he was sentenced.

Teixeira pleaded guilty earlier this year to six counts of willful retention and transmission of national defense information under the Espionage Act.

"I wanted to say I'm sorry for all the harm that I brought and caused," Teixeira said before the judge.

"I understand all the responsibility and consequences fall upon my shoulders alone and accept whatever that will bring," he added.

'A very heavy price'

The 2023 leak was the most damaging breach in more than a decade, with some of the documents relating to provision of equipment to Ukraine.

The security breach raised concerns over Washington's ability to protect its mostly closely guarded secrets and forced the Biden administration to scramble in a bid to contain the diplomatic and military fallout.

Speaking at a press conference after the sentencing, acting US Attorney Joshua Levy said Teixeira "has paid a very heavy price for the laws he broke and the damaged he caused."

"Anyone who willfully threatens national security by illegally disseminating classified information will face serious repercussions," he added.

ftm/zc (AP, AFP, Reuters)