London : A high profile defector has warned that North Korean hackers may launch attacks capable of destroying critical infrastructure and even killing people. According to BBC, Prof Kim Heung-Kwang said that North Korea has almost 6,000 trained military hackers. The warning came following last year’s Sony Pictures hack which was attributed to North Korea. Korean technology expert Martyn Williams asserted that the threat was “theoretical” in nature while Heung-Kwang called for international organisations to step in to prevent North Korea launching more severe attacks. Kim taught computer science at Hamheung Computer Technology University for 20 years, before escaping the country in 2004.