At one point, near the village of Etah, 100 miles NNE of the Thule Air base in a Greenland, the Island of a Greenland is only 30-40 miles from Canada.
They nearly touch.
https://www.peterson.af.mil/Units/821st-Air-Base-Group/
https://www.google.com/maps/place/Thule+Air+Base/@77.7506549,-78.8551842,5.46z/