The National Security Agency (abbreviated to NSA) is an intelligence gathering agency in the US which is part of the American Intelligence Community and under the jurisdiction of the Department of Defense.
The National Security Agency monitor vast numbers of phone calls and data transmissions with the goal of protecting the interests of the United States and its citizens. In late 1993 the NSA monitored a fax sent from Sioux City Police Station by Fox Mulder to Daniel Bernstein at the Crypography Section of the FBI. The fax was highlighted because it contained pictographs of a binary string fragment of a defense satellite transmission. The NSA responded to this apparent security leak by questioning Mulder and Dana Scully; his partner on the X-Files. This then led them to the source, a boy named Kevin Morris who had apparently transcribed the binary string from meaningless TV static.
After ransacking the Morris household looking for evidence they detained the boy and his mother, Darlene Morris. After several hours, the NSA released the two as they were unable to draw any conclusions about how the information made it to the public domain (TXF: "Conduit").