When the U.S. unleashed its Stuxnet cyber attack to sabotage Iran's nuclear weapons program about five years ago, it also attempted to carry out a similar plan against North Korea but ultimately failed, according to a report. 

The National Security Agency tried to infect the computers that control North Korea's nuclear weapons with a virus that would've caused the centrifuges necessary to enrich uranium to tear themselves apart -- what happened when Stuxnet ravaged Iran's nuclear weapons appartus.

However, due to North Korea's extreme isolation from the rest of the world, the U.S. was never able to inject the virus into the Asian country's systems, said Reuters, which reported the news on Friday, May 29, citing numerous named and unnamed U.S. intelligence sources. But unlike Iran, where many use the Internet, only an elite few in North Korea have access to it. 

North Korea is now only the second country that the U.S. is known to have targeted as part of a cyber espionage campaign that would've destroyed equipment. It is still unknown how the U.S. was able to introduce Stuxnet into Iran's computers. The NSA declined to comment on the Iran and North Korea cyber attacks.