Need.

ICBM stands for intercontinental ballistic missile — a long-range missile that takes advantage of the scientific laws of flight trajectory. The concept was born in the cold war, when new atomic bombs, or warheads, were developed in an attempt to maintain military superiority over the Soviet Union. As the arms race progressed, it became clear that a new delivery system for warheads had to be developed. Atomic weaponry could be placed on bombers, as it had been in World War II, but the bombers had to be kept on constant alert, which meant that some planes were flying all the time. The bombers were vulnerable to attack by antiaircraft defense systems, and the effectiveness of the warheads was limited by the number of planes carrying them that could reach their targets. A more effective delivery system had to be developed.

Rocketry.

The science of...