sentences:  It was closed in 1987.It was operated as part of the Pinetree Line network controlled by NORAD.As a result of the Cold War and with the expansion of a North American continental air defence system, Lowther was selected as a site for a United States Air Force (USAF) radar station, one of the many that would make up the Pinetree Line of Ground-Control Intercept (GCI) radar sites.