What was the “missile gap” identified in the 1950s?

The “missile gap” was the belief in the 1950s that the Soviet Union had moved ahead of the United States in intercontinental ballistic missile (ICBM) capability. Reports and political claims raised fears that the USSR had more or better long-range missiles, though later evidence showed the feared gap was exaggerated. So the best answer is that the USSR was reported to be ahead in ICBM technology.

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