The National Security Agency (NSA) is a United States intelligence agency responsible for global monitoring, collection, decoding, translation and analysis of information and data for foreign intelligence and counterintelligence purposes – a discipline known as Signals intelligence (SIGINT). NSA is also charged with protection of U.S. government communications and information systems against penetration and network warfare. The agency is authorized to accomplish its mission through clandestine means, among which are bugging electronic systems and allegedly engaging in sabotage through subversive software. 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. Unlike the Defense Intelligence Agency (DIA) and the Central Intelligence Agency (CIA), both of which specialize primarily in foreign human espionage, the NSA has no authority to conduct human-source intelligence gathering, although it is often portrayed doing so in popular culture. Instead, the NSA is entrusted with coordination and deconfliction of SIGINT components of otherwise non-SIGINT 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. NSA surveillance has been a matter of political controversy on several occasions, such as its spying on prominent 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. It has also created or maintained security vulnerabilities in most software and encryption, leaving the majority of the Internet susceptible to cyber attacks from the NSA and other parties. Internationally, in addition to the various data sharing concerns that persist, research has pointed to the NSA’s ability to surveil the domestic internet traffic of foreign countries through “boomerang routing”.