“For years, doctrine called for nukes to be used in Poland and East Germany when the Russians broke through in Germany.”
Back during Reagan’s time midgetman mobile launchers were planned but never deployed. We always relied on land-based (silos) ICBMs and our huge numbers of airborne delivered nukes.
“Why not use them against the passes on the Afghan/Pak border?”
That would be the current India nuke plan.
Not exactly correct. Historically, portable systems were used for tactical nukes (which would have been used against eastern Europe instead of the strategic weapons). While the Bushite NeoCons generally unilaterally disarmed with regard to tactical nukes, the Russians certainly have not done so. The US does still have some sub launched nuclear cruise missiles and some tactical nuclear bombs that can be dropped from aircraft, but has abandoned all surface delivery systems.
You may be too young to know about the Davy Crocket (not quite man portable, but close) that fired a small, approximately 75 pound shell, the huge 280mm atomic cannon, and the more prolific 155 mm artillery shells that could be fired from the common howitzers.
So, no, we did not "always rel(y) on land-based (silos) ICBMs and our huge numbers of airborne delivered nukes." We used to have tools to fit any need.