[PlasmaKrab]

Marcello, I think we can write off the advance planning argument in the Cold-War-Germany scenario, don't you? If we are assuming a fixed NATO forward defence against a Soviet push, then the NATO demolition/obstacle work would have taken place on friendly ground.
Granted, after the attack alert it wouldn't probably have remained friendly for very long, but remember that engineer units on both sides had literally decades to think up and plot contingency plans including what to blow up, where and when. I don't think charges were planted in advance (though the shelf life of modern explosives would certainly have allowed it), but possibly some emplacements had already been drilled and readied.
Come to think of it, and given the defense policy and the political climate in FRG, I wouldn't rule out that some strategic infrastructure was designed with the task of permanently blocking them in mind.