A 21-year-old national guardsman is facing 15 years in prison if found guilty of leaking some of America’s most closely guarded secrets as it emerged he used his security clearance to follow the investigation as it closed in on him.

Jack Teixeira, was charged with two counts under the Espionage Act in Boston on Friday over the most damaging leak of US intelligence in a decade.

They are the unauthorised detention and transmission of national defence information and the unauthorised removal and retention of classified material. The counts carry prison sentences of 10 years and five years respectively. Prosecutors could still bring additional charges. The US attorney-general, Merrick Garland, said there were “very serious penalties” associated with the crimes.

“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 ournational security,” Garland said.

President Joe Biden said he had directed the US military and intelligence community to restrict the “distribution of sensitive information” following the leak which has caused international embarrassment for the country.

The documents, which detailed US concern over Ukraine’s ability to fend off the Russian invasion, as well as sensitive information on its allies, were first leaked on Discord, a social media platform popular with gamers.Many of the documents included “TOP SECRET” markings, the FBI said in a criminal complaint filed in court.

Teixeira was arrested by heavily armed tactical agents at his home in North Dighton, Massachusetts, on Thursday following a frenzied, week-long search for the source of the leak.

Investigators began focusing on Teixeira after he was detected using his government computer to search for the word “leak” in a classified intelligence system, an FBI affidavit revealed.

He began searching on April 6, the day The New York Times first published a story about the breach of documents, suggesting he was trying to find out about the investigation into the leaker.

Hundreds of classified documents were leaked onto a private group on Discord beginning in December, but it appears the breach went unnoticed until some of the documents were forwardedto a number of other groups and platforms earlier this month.

The Daily Telegraph, London