National Security Agency

The National Security Agency (NSA) is an intelligence organization of the United States government, responsible for global monitoring, collection, and processing of information and data for foreign intelligence and counterintelligence purposes – a discipline known as signals intelligence (SIGINT). NSA is concurrently charged with protection of U.S. government communications and information systems against penetration and network warfare. Although many of NSA's programs rely on "passive" electronic collection, the agency is authorized to accomplish its mission through active clandestine means, among which are physically bugging electronic systems and allegedly engaging in sabotage through subversive software. Moreover, NSA maintains physical presence in a large number of countries across the globe, where its Special Collection Service (SCS) inserts eavesdropping devices in difficult-to-reach places. SCS collection tactics allegedly encompass "close surveillance, burglary, wiretapping, breaking and entering".

Unlike the Defense Intelligence Agency (DIA) and the Central Intelligence Agency (CIA), both of which specialize primarily in foreign human espionage, NSA does not unilaterally conduct human-source intelligence gathering, despite often being portrayed so in popular culture. Instead, NSA is entrusted with assistance to and coordination of SIGINT elements at other government organizations, which are prevented by law from engaging in such activities without the approval of the NSA via the Defense Secretary. As part of these streamlining responsibilities, the agency has a co-located organization called the Central Security Service (CSS), which was created to facilitate cooperation between NSA and other U.S. military cryptanalysis components. Additionally, the NSA Director simultaneously serves as the Commander of the United States Cyber Command and as Chief of the Central Security Service.

Originating as a unit to decipher coded communications in World War II, it was officially formed as the NSA by Harry S. Truman in 1952. Since then, it has become one of the largest of U.S. intelligence organizations in terms of personnel and budget, operating as part of the Department of Defense and simultaneously reporting to the Director of National Intelligence.

NSA surveillance has been a matter of political controversy on several occasions, such as its spying on anti-Vietnam war leaders or economic espionage. In 2013, the extent of the NSA's secret surveillance programs was revealed to the public by Edward Snowden. According to the leaked documents, the NSA intercepts the communications of over a billion people worldwide and tracks the movement of hundreds of millions of people using cellphones. Internationally, research has pointed to the NSA's ability to surveil the domestic internet traffic of foreign countries through "boomerang routing".

https://en.wikipedia.org/wiki/National_Security_Agency