US National Security Agency (NSA)

The U.S. National Security Agency (NSA; abbreviation: NSA) is the most highly classified intelligence agency in the U.S., and also the intelligence agency with the largest expenditure and the largest number of employees in the U.S. The NSA is a department of the Department of Defense. The U.S. government receives more than 90% of intelligence from the NSA, which is ostensibly a department of the Department of Defense, but is actually a presidential direct control department, is the hub of all U.S. intelligence agencies, can supervise U.S. intelligence agencies and senior officials, including the Central Intelligence Agency, the Federal Bureau of Investigation, and so on.