Four members of an international hacking team were charged with infiltrating U.S. Army and prominent technology companies’ computer networks to steal Xbox information and sensitive military manuals, the Department of Justice announced Tuesday. The alleged theft included information from the games “Call of Duty: Modern Warfare 3,” “Gears of War 3” and other data totaling more than $100 million in intellectual property.

Perhaps most alarmingly, the ring is accused of stealing Apache helicopter simulator software information developed by Boeing for training U.S. soldiers. The hackers also allegedly stole pre-release copies of the aforementioned games as well as trade secrets related to the then-unreleased Xbox One gaming console.

Nathan Leroux, 20, of Bowie, Maryland; Sanadodeh Nesheiwat, 28, of Washington, New Jersey; David Pokora, 22, of Mississauga, Ontario, Canada, and Austin Alcala, 18, of McCordsville, Indiana, were indicted by a grand jury April 23. Pokora and Nesheiwat pleaded guilty to conspiracy to commit computer fraud and copyright infringement after the indictment was unveiled Tuesday. Sentencing was scheduled for January.

“These were extremely sophisticated hackers,” Assistant U.S. Attorney Ed McAndrew told the Guardian after a court hearing Tuesday. “Don’t be fooled by their ages.”

McAndrew explained the FBI’s Delaware office was alerted to the hack in January 2011 by a confidential informant. Microsoft and Zombie Studios, a Seattle company involved in the production of Apache flight simulator software, helped in the investigation, he said.

Pokora’s plea, the Justice Department said, is believed to be the first conviction of a foreign-based individual for hacking into an American business network to steal protected trade information. He was apprehended trying to enter the country from Canada at Lewiston, New York.

Both Boeing and Microsoft, which manufactures the Xbox, have been targeted previously by hackers, often from outside North America. Chinese hackers seem to have been especially aggressive, with thieves working to steal military and business secrets. The Justice Department earlier this year charged a Chinese businessman with stealing data on F-22 and F-35 fighter planes as well as the C-17 cargo plane program.