U.S. Spies Tapped North Korean Computers Prior to Sony Hack

U.S. spies began monitoring North Korean government Internet activity years before that country’s suspected hack of Sony Pictures Entertainment, according to people familiar with the surveillance and a document that is part of a cache of newly disclosed materials casting light on American cyber-espionage efforts.

People familiar with the espionage, who asked not to be identified discussing classified activities, say some of it backtracked through servers used by North Korea in China, Southeast Asia and elsewhere. The document, which the German magazine Der Spiegel said came from former National Security Agency contractor Edward Snowden, indicates that U.S. intelligence officials began by piggybacking onto computer spying already being done by South Korea.