Washington, June 16 : The US air national guardsman, accused of leaking classified documents involving intelligence on the Russia-Ukraine war and others, was indicted by a federal grand jury on charges of unlawful disclosure of national defence information. Jack Teixeira, 21, of the Massachusetts Air National Guard, was indicted on Thursday in Boston on six counts of willful retention and transmission of classified information relating to the national defense, Xinhua news agency reported, citing a statement issued by the Department of Justice. "As laid out in the indictment, Jack Teixeira was entrusted by the United States government with access to classified national defence information - including information that reasonably could be expected to cause exceptionally grave damage to national security if shared," said US Attorney General Merrick Garland while announcing the indictment. "Teixeira is charged with sharing information with users on a social media platform he knew were not entitled to receive it. In doing so, he is alleged to have violated US law and endangered our national security," he added. The young airman was arrested in April and has been detained ever since. He was alleged to have leaked classified documents from the Department of Defense. The leaked materials were first shared by Teixeira with his friends on Discord - an online chatting app mostly attracting video gamers. /IANS