[Imp]

Never really bothered me because if you have armour around fortifications are history from the 70s on anyway. Never waste ATGMs on them though you play USMC a bit I guess so tanks could be in short supply. Think the only time I ever tried it was in an Afghanistan battle as my 2 ATGM teams were twiddling there thumbs.
Because they are so easy to destroy with modern tank guns I did wonder however about using something similar to the way reactive armour works for the heavier fortifications to represent "chipping away at it"