These 17 Agencies Make Up The Most Sophisticated Spy Network In The World

The U.S. intelligence community is vast, composed of 17 distinct organizations each operating under its own shroud of secrecy.

Oversight of these agencies generally falls to the Department of Defense or Congress, leaving the average citizen with precious little knowledge of how they operate.

Funded by largely classified budgets, it's difficult to assess how much the U.S. annually spends on these clandestine operations, but one 2012 estimate pegs the cost at about $75 billion.

The following slides highlight the expansive reach of the U.S. intelligence community.

The Central Intelligence Agency spies on foreign governments and organizes covert ops.

The CIA is the most well-known U.S. spying agency, formed by the passage of the National Security Act of 1947. The agency has its roots with the Office of Strategic Services (OSS) that operated during World War II.

Headquarters: Langley, Va.

Mission: CIA collects, analyzes, and disseminates intelligence gathered on foreign nations. This comes through signals and human intelligence sources.

Budget: Classified. On their website, the CIA states, "neither the number of employees nor the size of the Agency's budget can, at present, be publicly disclosed. A common misconception is that the Agency has an unlimited budget, which is far from true."

There have been some slips, however. In 2005, a CIA deputy director inadvertently revealed the annual intelligence budget was $44 billion.

The National Security Agency was once so secretive it was jokingly called 'No Such Agency.'

The NSA was established in 1952 with a mission primarily dedicated to code breaking, after the Allies' success in cracking German and Japanese codes during World War II. For a long time, the NSA, which operates under the Dept. of Defense, was not even recognized by the government, commonly referred to as "No Such Agency."

Headquarters: Fort Meade, Md.

Mission: The main functions of the NSA are signals intelligence — intercepting and processing foreign communications, cryptology — cracking codes, and information assurance. IA is, put simply: preventing foreign hackers from getting secret information.

Budget: Classified. Some estimate the NSA is actually the largest intelligence organization in the world — three times the size of the CIA. The headquarters alone takes up 6.3 million square feet — around the same size as the Pentagon — with 112 acres of parking spaces, reports the Washington Post.

The Defense Intelligence Agency works to understand what foreign militaries will do before they do it.

The DIA was established in 1961 with the goal of sharing information collected by the major military intelligence outfits (such as Army or Marine Corps Intelligence). More recently, the DIA has been expanding its overseas spy network to collect first-hand intelligence.

Headquarters: Washington, D.C.

Mission: The DIA serves as the lead intelligence agency for the Dept. of Defense, coordinating analysis and collection of intelligence on foreign militaries, in addition to surveillance and reconnaissance operations. The DIA is the common link between military and national intelligence agencies.

Budget: Classified. The DIA does not reveal budget information, although they do say they have more than 16,500 men and women working for them and are under DoD and congressional oversight.

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