North Korean hackers are believed to have stolen a large amount of classified military documents, including a South Korean-U.S. plan to "decapitate" its leadership, South Korean news agency Yonhap reported Tuesday.
According to the news agency, Democratic Party Rep. Lee Cheol-hee said the hackers broke into South Korea's Defense Integrated Data Center, which stores digital military data, in September 2016 to steal the secret files.
Among the files was Operational Plan 5015, Yonhap said. That plan relates to "the latest Seoul-Washington plan to handle an all-out war with Pyongyang, which reportedly contains detailed procedures to 'decapitate' the ," according to Yonhap.
Another stolen file, Operational Plan 3100, is Seoul's plan to "respond to the North's localized provocations," the news agency added.
The South Korean lawmaker, a member of the ruling party, cited unidentified defense officials as being the sources of information on the hack. He said that 235 gigabytes worth of military documents were taken, and nearly 80 percent had yet to be identified.
"Also among them were contingency plans for the South's special forces, reports to allies' top commanders, and information on key military facilities and power plants," he said, according to Yonhap.
The Democratic Party, led by President Moon Jae-in, came to power in the May election after the impeachment of Park Geun-hye, who was head of the Saenuri Party. The reported hacking took place while she was president.