Chinese spies stole “many terabytes of data” relating to the US’ F-35 Joint Strike Fighter, as well as other top-secret US military projects, according to confidential documents released to German magazine Der Spiegel by former National Security Administration (NSA) contractor Edward Snowden.
The theft of the fighter plans was reported in 2013, but this is the first time that the incident has been confirmed by top-secret documents from within the US government itself.
The incident is detailed in an NSA assessment of Chinese cyber-spying activity on US targets, an edited version of which Der Spiegel released on Saturday along with other documents detailing the US’ cyber-espionage activities against both its rivals and its allies.
According to the leaked NSA assessment, Chinese spies stole documents that detail the Lockheed Martin F-35 Lightning II’s radar systems, engine schematics and methods for cooling exhaust gases.
The theft has previously been reported to have taken place at Lockheed Martin’s facilities in 2007.
Chinese hackers breached carried out more than 500 “significant intrusions” into US Defence Department systems in a single year, with damage assessment and remediation efforts costing more than $100m (£66m), according to the leaked NSA documents.
50 terabytes of data stolen
These operations, collectively code-named “Byzantine Hades”, resulted in the theft of information relating to the B-2 stealth bomber, the F-22 Raptor stealth fighter, nuclear submarine and naval air-defence missile designs, and tens of thousands of military personnel records, according to the leaked documents.
They estimate the total amount of data stolen at 50 terabytes, or “five Libraries of Congress”.
The Chinese government dismissed the allegations contained in the NSA documents, with a Foreign Ministry spokesman calling them “completely unjustified”.
The documents also discuss the NSA’s infiltration of North Korea’s computer systems with the aid of South Korea. Unnamed US officials told the New York Times in a report published on Sunday that this spying programme provided data that helped the US conclude North Korea was responsible for the hack of Sony Pictures in November.