For more than 40 years after 1945, the world was dominated by confrontation between two major power blocks, led by the United States and the Soviet Union. One of the most menacing and potent symbol was of this was the nuclear bomber. During the first phase of the Cold War, this was the dominant weapon. Both sides maintained large fleets of nuclear bombers at a high level of readiness. They also continually probed each other's air defenses, to discover weak points in them