The National Security Agency (NSA) was established by Presidential directive in 1952 by President Truman. As a separately organized agency within the Department of Defense (DOD), NSA plans, coordinates, directs, and performs foreign signals intelligence (SIGINT) and information security (INFOSEC) functions.

Under a 1986 law, NSA became a combat support agency of the DOD to ensure an informed, alert and secure environment for US war fighters and policymakers.

The fundamental mission and core competency of NSA is cryptology. The NSA strives to maintain a global advantage which requires preservation of a healthy cryptologic capability in the face of technical challenges.

The SIGINT mission strives for an effective, unified organization and control of all the foreign signals collection and processing activities of the United States. In its SIGINT role, NSA intercepts and analyzes foreign electromagnetic signals, deciphers the ciphers and produces intelligence information for decision makers and military commanders.

The INFOSEC mission is driven to guarantee vital information by being the preferred provider of leadership, products, and services for NSA's customers and also to be innovative in seeking the technological advantages needed to succeed.