US/NATO doctrine was to use tactical nukes in the event of an invasion of West Germany. There were tactical nuclear mines, tactical nuclear bridge demolition charges, tactical nuclear artillery shells, etc. In the 50s the US reorganized around a Pentomic division [1], which was effectively highly mobile battlegroups too small to be worth nuking since the assumption was that any reasonable sized formation would get plastered.

[1]https://en.wikipedia.org/wiki/Pentomic