The SIGINT mission is specifically limited to gathering information about international terrorists and foreign powers, organizations, or persons. NSA produces intelligence in response to formal requirements levied by those who have an official need for intelligence, including all departments of the Executive Branch of the United States Government.

As sensitive information is often encrypted, signals intelligence often involves the use of cryptanalysis and traffic analysis which is the process of identifying who is signaling whom and in what quantity. This can often produce valuable information, even when the messages themselves cannot be decrypted.