North Korea may have stolen U.S. fighter jet blueprints in a recent cyberattack

The theft was the result of an attack on South Korean companies and government agencies that ultimately compromised 140,000 computers, Reuters reports. A total of 40,000 defense-related materials were stolen, including the blueprints for wings of F-15 fighter jets. These blueprints appear to have been obtained from Korean Air Lines, which serves as a contract manufacturer for the military of South Korea.

“North Korea turns out to have been preparing for a long time to try to launch a countrywide cyberattack,” South Korea’s Korean National Police Agency said.

But the rival country claims no wrongdoing, denying any involvement in a cyberattack or hacking attempt. This isn’t the first time the isolationist nation has faced accusations of cyber espionage from foreign countries. In 2014, the U.S. accused North Korea of attacking Sony as retribution for the controversial film The Interview. Again, North Korea said it was not involved in any such attack.

While the hackers appear to have infiltrated South Korean systems quite some time ago (it is likely that the attacks began in 2014), country officials say that little sensitive information was compromised. “The leak will likely have a negligible impact on national security,” a South Korean official noted in a statement. But still, as tensions continue to mount between North Korea and the rest of the world, the nation’s cyber activity is increasingly becoming a topic of interest for the U.S. and its allies.