Originating as a unit to decipher coded communications in World War II, it was officially formed as the NSA by President Harry S. Truman in 1952. Since then, it has become one of the largest U.S. intelligence organizations in terms of personnel and budget. The NSA currently conducts worldwide mass data collection and has been known to physically bug electronic systems as one method to this end. The NSA has also been alleged to have been behind such attack software as Stuxnet, which severely damaged Iran's nuclear program. The NSA, alongside the Central Intelligence Agency (CIA), maintains a physical presence in many countries across the globe; the CIA/NSA joint Special Collection Service (a highly classified intelligence team) inserts eavesdropping devices in high value targets (such as Presidential palaces or embassies). SCS collection tactics allegedly encompass "close surveillance, burglary, wiretapping, breaking and entering".
Unlike the CIA and the Defense Intelligence Agency (DIA), both of which specialize primarily in foreign human espionage, the NSA does not publicly conduct human-source intelligence gathering. The NSA is entrusted with providing assistance to, and the coordination of, SIGINT elements for other government organizations - which are prevented by law from engaging in such activities on their own. As part of these responsibilities, the agency has a co-located organization called the Central Security Service (CSS), which facilitates cooperation between the NSA and other U.S. defense cryptanalysis components. To further ensure streamlined communication between the signals intelligence community divisions, the NSA Director simultaneously serves as the Commander of the United States Cyber Command and as Chief of the Central Security Service.
The NSA's actions have been a matter of political controversy on several occasions, including its spying on anti-Vietnam-war leaders and the agency's participation in economic espionage. In 2013, the NSA had many of its secret surveillance programs revealed to the public by Edward Snowden, a former NSA contractor. According to the leaked documents, the NSA intercepts and stores the communications of over a billion people worldwide, including United States citizens. The documents also revealed the NSA tracks hundreds of millions of people's movements using cellphones metadata. Internationally, research has pointed to the NSA's ability to surveil the domestic Internet traffic of foreign countries through "boomerang routing".
The origins of the National Security Agency can be traced back to April 28, 1917, three weeks after the U.S. Congress declared war on Germany in World War I. A code and cipher decryption unit was established as the Cable and Telegraph Section which was also known as the Cipher Bureau. It was headquartered in Washington, D.C. and was part of the war effort under the executive branch without direct Congressional authorization. During the course of the war it was relocated in the army's organizational chart several times. On July 5, 1917, Herbert O. Yardley was assigned to head the unit. At that point, the unit consisted of Yardley and two civilian clerks. It absorbed the navy's Cryptanalysis functions in July 1918. World War I ended on November 11, 1918, and the army cryptographic section of Military Intelligence (MI-8) moved to New York City on May 20, 1919, where it continued intelligence activities as the Code Compilation Company under the direction of Yardley.
After the disbandment of the U.S. Army cryptographic section of military intelligence, known as MI-8, in 1919, the U.S. government created the Cipher Bureau, also known as Black Chamber. The Black Chamber was the United States' first peacetime cryptanalytic organization. Jointly funded by the Army and the State Department, the Cipher Bureau was disguised as a New York City commercial code company; it actually produced and sold such codes for business use. Its true mission, however, was to break the communications (chiefly diplomatic) of other nations. Its most notable known success was at the Washington Naval Conference, during which it aided American negotiators considerably by providing them with the decrypted traffic of many of the conference delegations, most notably the Japanese. The Black Chamber successfully persuaded Western Union, the largest U.S. telegram company at the time, as well as several other communications companies to illegally give the Black Chamber access to cable traffic of foreign embassies and consulates. Soon, these companies publicly discontinued their collaboration.