From early days of biplanes to today's spy satellites, the spies in the sky have proved to be an enduring component of modern warfare.

In WWII, the U.S. stayed ahead of the Soviet Union in the race for atomic bombs, but the Soviets genius for espionage allowed them to acquire atomic secrets of their own.

Bletchley Park, an unassuming Victorian mansion 50 miles north of London, became the most potent deciphering center of WWII when its staff of code breakers cracked the Nazis' encrypting machine.

Born in the crucible of Israel's war of independence and honed in the struggle for survival against hostile neighbors, the Mossad intelligence service gained a reputation for ruthlessness.

See how the spectacular successes of Britain's Secret Intelligence Service, like breaking the Enigma code during World War II, were offset by devastating failures such as its inability to detect superspy Kim Philby.

Learn about the history and reach of the Komitet Gosudarstvennoe Bezopasnosti (Committee for State Security), the agency of the former Soviet Union responsible for state security from 1954 to 1991.