“The US government and various security researchers have connected Iran to a number of egregious cyberattacks in the past, including one launched against the Navy. And based on a 2013 NSA document leaked by Edward Snowden that The Intercept has just published, they’ve also long suspected that Iranian officials learned cyberwarfare from the West’s previous attacks against the country’s computers. The NSA is also apparently worried that the country’s cyberweapons are becoming more and more potent, as it continues to improve and not just replicate its enemies tactics. As you might have guessed, Iran’s crusade to give its enemies a taste of their own medicine began with the attacks against its nuclear facility.”
http://www.engadget.com/2015/02/10/nsa-iran-cyberwarfare/
For further reading on this topic:
Wired: An Unprecedented Look at Stuxnet, the World’s First Digital Weapon
This article provides a very detailed overview of the stuxnet operation:
“Stuxnet, as it came to be known, was unlike any other virus or worm that came before. Rather than simply hijacking targeted computers or stealing information from them, it escaped the digital realm to wreak physical destruction on equipment the computers controlled.”
https://www.wired.com/2014/11/countdown-to-zero-day-stuxnet/
NYTimes: Nuclear Facilities in 20 Countries May Be Easy Targets for Cyberattacks
“WASHINGTON — Twenty nations with significant atomic stockpiles or nuclear power plants have no government regulations requiring minimal protection of those facilities against cyberattacks, according to a study by the Nuclear Threat Initiative.
The findings build on growing concerns that a cyberattack could be the easiest and most effective way to take over a nuclear power plant and sabotage it, or to disable defenses that are used to protect nuclear material from theft. The countries on the list include Argentina, China, Egypt, Israel, Mexico and North Korea.”
IR Theory & Practice 