Also ''North Warning System'': https://en.wikipedia.org/wiki/North_Warning_System https://en.wikipedia.org/wiki/North_Warning_System which superceded the ''DE

Also ''North Warning System'': https://en.wikipedia.org/wiki/North_Warning_System https://en.wikipedia.org/wiki/North_Warning_System which superceded the ''DEW Line'' and ''Pinetree Line'': https://en.wikipedia.org/wiki/Distant_Early_Warning_Line https://en.wikipedia.org/wiki/Distant_Early_Warning_Line https://en.wikipedia.org/wiki/Pinetree_Line https://en.wikipedia.org/wiki/Pinetree_Line