Jack Teixeria, the Air National guardsman accused of leaking classified documents online, was indicted Thursday by a federal grand jury in Boston.
The 21-year-old is facing six counts of willful retention and transmission of national defense information, according to the Department of Justice.
If convicted of the crimes, he could face up to 10 years in prison for each charge and a fine of up to $250,000.
"The unauthorized removal, retention and transmission of classified information jeopardizes our nation's security. Individuals granted access to classified materials have a fundamental duty to safeguard the information for the safety of the United States, our active service members, its citizens and its allies," Acting United States Attorney Joshua S. Levy said in a statement.
"We are committed to ensuring that those entrusted with sensitive national security information adhere to the law," he added.
Teixeria, who was arrested in April, is facing charges of sharing highly classified military documents about the war in Ukraine, in addition to other top national security issues, on the popular social media website Discord.
At the behest of prosecutors, a federal judge had ordered Teixeira to remain behind bars until his trial.
"He has an enormous incentive to flee, and there are numerous adversaries of the United States that could provide him the means to do so, regardless of the conditions set by the Court," the prosecutors argued in their motion for pretrial detention.