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The Distant Early Warning Line, also known as the DEW Line or Early Warning Line, was a system of radar stations in the far 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 Soviet bombers during the Cold War, and provide early warning of any sea-and-land invasion. The DEW Line was operational from 1957 to the late 1980s and it was the northernmost and most capable of three radar lines in Canada and Alaska; the joint Canadian-US Pinetree Line ran from Newfoundland to Vancouver Island, and the Mid-Canada Line ran somewhat north of this. Between 1988 and 1993, most stations were deactivated. Those that remained were upgraded as part of the new North Warning System. ==Introduction== The shortest (great circle) route for a Russian air attack on North America is through the Arctic, across the North Pole. The DEW Line was built during the Cold War to give early warning of a Soviet nuclear strike, to allow time for US bombers to get off the ground and land-based ICBMs to be launched, to reduce the chances that a preemptive strike could destroy US strategic nuclear forces. The original DEW line was designed to detect bombers and was unable to detect intercontinental ballistic missiles (ICBMs). To give warning of this threat, in 1958 a more sophisticated radar system was constructed, the Ballistic Missile Early Warning System (BMEWS). The DEW Line was a significant achievement among Cold War initiatives in the Arctic. A successful combination of scientific design and logistical planning of the late 1950s, the DEW Line consisted of a string of continental defence radar installations, ultimately stretching from Alaska to Greenland. In addition to the secondary Mid-Canada Line and the tertiary Pinetree Line, the DEW Line marked the edge of an electronic grid controlled by the new SAGE (Semi Automatic Ground Environment) computer system and was ultimately centered at the Cheyenne Mountain Complex, Colorado, command hub of the North American Aerospace Defense Command (NORAD).〔(The DEW LINE Sites in Canada, Alaska & Greenland )〕 The construction of the DEW Line was made possible by a bilateral agreement between the Canadian and US governments, and by collaboration between the US Department of Defense and the Bell System of communication companies. The DEW Line grew out of a detailed study made by a group of the nation's foremost scientists in 1952, the Summer Study Group at the Massachusetts Institute of Technology. The subject of the study was the vulnerability of the US and Canada to aerial bombing attacks, and its concluding recommendation was that a ''distant early warning line'' of search radar stations be built across the Arctic border of the North American continent as rapidly as possible.〔(The DEW Line and Other Military Projects )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Distant Early Warning Line」の詳細全文を読む スポンサード リンク
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