預警系統
After World War II most, if not all, early warning networks had been dismantled. At the height of the Cold War, paranoia ran deep within the halls of the United States military establishment. By 1949, the USSR had developed the atomic bomb and the capacity to deliver it by air. The United States considered that it needed to protect itself from the Soviets, formerly allies. To this end, the US constructed early-warning stations. This system was called the Distant Early Warning system or the DEW Line, which was a state of the art product.