The US National Security Agency (NSA) started to interfere with North Korean computer networks more than five years ago, the New York Times reported.
This led to American officials taking a strong stance against Pyongyang and blaming North Korea for the cyber-attack on Sony Pictures Entertainment last year.
According to officials quoted by the newspaper and a leaked NSA document, the intelligence agency infiltrated North Korean systems aided by South Korea and other US allies after having had to first tap into China’s networks to gain online access to North Korea.
“At that point, our access to North Korea was next to nothing but we were able to make some inroads to the South Korea computer network exploitation (CNE),” said the document released by the German newspaper Spiegel.
Quoting officials, the New York Times said the classified security agency program morphed into an extensive effort to monitor the online activity of hackers in North Korea by placing malware. Knowledge of the intervention convinced the Obama administration to accuse North Koreans directly for the Sony attack.
Obama "had no doubt" in this case, a senior US military official told the Times.
The computer systems at the technology and entertainment giant went down in November last year. It is believed that North Korea was the culprit for the massive cyber-attack in retaliation for the Sony film ‘The Interview’, in which the main characters assassinate the communist state’s leader Kim Jong-Un.