On Tuesday, the U.S. Department of Justice unsealed charges against two more members of the Chinese Ministry of State Security (MSS) relating to a concerted effort to steal commercial aviation secrets from U.S. based companies. This marks the third time that members of the Chinese government have been directly implicated in espionage and the theft of commercial or military aviation technology or trade secrets since just September.

“The threat posed by Chinese government-sponsored hacking activity is real and relentless,” said John Brown, FBI Special Agent in Charge of the San Diego Field Office. “Today, the Federal Bureau of Investigation, with the assistance of our private sector, international and U.S. government partners, is sending a strong message to the Chinese government and other foreign governments involved in hacking activities. We are working together to vigorously investigate and hold hackers accountable regardless of their attempts to hide their illicit activities and identities.”

Zha Rong and Chai Meng, both intelligence officers in what could loosely be considered the Chinese equivalent of the American CIA, stand accused of conducting a sustained cyber intrusion campaign over the span of some five years. The campaign targeted 13 companies and was apparently focused specifically on stealing designs for turbofan engines commonly used on commercial passenger jets.

“State-sponsored hacking is a direct threat to our national security. This action is yet another example of criminal efforts by the MSS to facilitate the theft of private data for China’s commercial gain,” said U.S. Attorney Adam Braverman, in a Justice Department press release. “The concerted effort to steal, rather than simply purchase, commercially available products should offend every company that invests talent, energy, and shareholder money into the development of products.”