The Distant Early Warning Line, also known as the DEW Line or Early Warning Line, was a system of radar stations in the northern Arctic region of Canada, with additional stations along the north coast and Aleutian Islands of Alaska, in addition to the Faroe Islands, Greenland, and Iceland. It was set up to detect incoming bombers of the Soviet Union during the Cold War, and provide early warning of any sea-and-land invasion.

The Pinetree Line was a series of radar stations located across southern Canada at about the 50th parallel north, along with a number of other stations located on the Atlantic and Pacific coasts. Run by North American Aerospace Defense Command (NORAD), over half were staffed by United States Air Force personnel with the balance operated by the Royal Canadian Air Force. The line was the first coordinated system for early detection of a Soviet bomber attack on North America, but before the early 1950s radar technology quickly became outdated and the line was in full operation only for a short time.