Der Spiegel said its own analysis of leaked NSA documents showed the agency broke into the system in 2012. The documents also showed NSA experts discovered evidence the Chinese were also trying to crack the U.N. system.
The NSA's actions violated agreements protecting the United Nations from covert surveillance by its members, Der Spiegel said.
Documents leaked by former NSA contract analyst Edward Snowden showed the agency conducted surveillance on the European Union Embassy to the United Nations with maps showing the building's physical layout and the architecture of its information technology systems.
Der Spiegel also said the NSA has a monitoring system called the "Special Collection Service" with listening posts in 80 U.S. embassies and consulates worldwide. In most cases, the host countries are not aware of the posts.