According to his plea agreement, Pho kept both digital and hard copies of top secret national defense information at his residence in Maryland. Though the US government never confirmed it, the Wall Street Journal reported last year that some of the NSA data on Pho's home computer was stolen by Russian hackers after they identified it through the Kaspersky software running on his machine.

An all-out onslaught on Kaspersky followed, with the US first prohibiting federal agencies from using the software last September, and Trump later making the ban official with a bill: the National Defense Authorization Act (NDAA). Kaspersky has repeatedly denied the allegations and launched its own investigation that claimed Pho's computer was plagued with malware that could've been used to steal the secrets.

"As a result of his actions, Pho compromised some of our country's most closely held types of intelligence, and forced NSA to abandon important initiatives to protect itself and its operational capabilities, at great economic and operational cost," said Robert Hur, the US Attorney for the District of Maryland, in a statement.