National Security Agency surveillance
In 2018, after a FOIA request to release information about Main Core, the Department of Homeland Security replied that there were no "maincore" or "main core" identified in their records or archives.
The Main Core data, which is believed to come from the NSA, FBI, CIA, and other sources, is collected and stored without warrants or court orders. The database's name derives from the fact that it contains "copies of the 'main core' or essence of each item of intelligence information on Americans produced by the FBI and the other agencies of the U.S. intelligence community".
As of 2008[update], there were allegedly eight million Americans listed in the database as possible threats, often for trivial reasons, whom the government may choose to track, question, or detain in a time of crisis.