Report: US Hacked North Korea Years Ago Meanwhile, unknown hackers have trashed Kim Jong Un video game By Rob Quinn, Newser Staff Posted Jan 19, 2015 5:46 AM CST Updated Jan 19, 2015 7:12 AM CST 11 comments Comments North Korean students use computers in a classroom with portraits of late leaders Kim Il Sung, left, and his son Kim Jong Il hanging on the wall at the Kim Chaek University of Technology in Pyongyang. (AP Photo/Vincent Yu, File) (Newser) – The US was able to pin the Sony Pictures cyberattack on North Korea with confidence because the National Security Agency hacked its way into North Korean systems years earlier, according to the New York Times, which cites American and foreign officials as well as computer experts and a newly disclosed NSA document. The sources say that after gaining access to North Korean networks in 2010, the initial focus was on Pyongyang's weapons programs, but the US focus shifted to North Korea's "cyberarmy" after a massive hack in 2013 paralyzed South Korea's banking system. But although the NSA has reportedly placed malware in North Korean systems intended to serve as an early warning system for cyberattacks, the monitoring didn't give US agencies any advance warning of the Sony attack, officials tell NBC. The penetration did, however, make it easier to trace what one insider calls North Korea's "incredibly careful and patient" preparation for the attack. "Attributing where attacks come from is incredibly difficult and slow,” a cyberwarfare expert tells the Times. "The speed and certainty with which the United States made its determinations about North Korea told you that something was different here—that they had some kind of inside view." In what appears to be an unrelated attack, developer Moneyhorse Games halted work on its "Glorious Leader!" action game starring Kim Jong Un after unidentified hackers destroyed game data and locked the company out of its own computers, Engadget reports.