The NSA has been collecting around 5 billion phone records a day on the whereabouts of cell phones outside the US. It is doing so to keep tabs on people's movements and to monitor suspicious travel patterns and activities for intelligence purposes.
According to the report, the NSA can access billions of phone records by monitoring mobile phone networks. The programmes and databases designed to analyze this data have become a powerful surveillance tool, enabling the NSA to track people in a unique way.
In the USA, the monitoring of cell phone networks worldwide has not raised many questions yet. However, the American Civil Liberties Union protested that gathering cell phone data on an international scale is not a good idea. They said this monitoring by the NSA is troubling for Americans.
The NSA's overseas monitoring programme sifts through huge numbers of records and flags suspicious activity, such as a terrorist planning or a series of telephone calls preceding an attack. Moreover, the agency's algorithms, like methods used to track areas where people have a contagious disease, could help control that disease by enabling immediate action.
For criminal investigations, the use of mobile phone tracking data is an effective method for locating a suspect.