A senior US official revealed late Wednesday that the National Security Agency spied on Americans until a judge ruled that program illegal in 2011. The official, who didn\'t want to be named, said that the NSA\'s surveillance of Americans was \"due to a technological problem\" and not \"an overreach\" by the agency. The NSA is said to have diverted the flow of international data through fiber-optic cables in the US, resulting in the tech error. The documents recently declassified by the government demonstrate \"the strong nature of the oversight of this program,\" according to the official. The Foreign Intelligence Surveillance Court (FISA), which is responsible for reviewing the legality of spying programs, released the documents amid the heated controversy that began when former NSA contractor Edward Snowden - now declared a fugitive in Russia - revealed how the NSA mass-collects phone data. The court\'s move suggested a small step toward transparency and a willingness to admit mistakes were made. The official US position is that the NSA does not spy on American citizens on American soil.