In 1948, the Soviet Union unveiled a new long-range bomber, similar in design and performance to the American B-29 bomber. The following year, the Soviets detonated its first nuclear weapon. By 1950, both the Canadian and American government recognized that the main threat to North American security was a long-range Soviet bomber force. Consequently, the two governments cooperated in the construction of three warning lines, networks of radar stations positioned across North America.
The Pine Tree line was a series of radar installations along the 49th parallel. The Mid-Canada line was built along the 55th parallel, and the DEW (Distant Early Warning) line stretched from Alaska to Greenland along the Arctic coast of North America. In the event of a Soviet bomber attack, these radar installations would provide Canadian and American air forces four to six hours warning. Both Royal Canadian Air Force (RCAF) and United States Air Force (USAF) fighters could be deployed to intercept any Soviet bomber force.