With the Pluton tracked missile system in place, France doesn’t need to add more defenses, since her strategy is to make Germany impassable by tactical nuclear strikes with the Plutons: thus turning Germany into denied ground, and a nuclear wasteland as a byproduct. This is entirely within the bounds of the usual French conduct towards France’s Allies.
As there is unlikely to be an attack from any other direction than east, France has little need to worry. After all: apart from loony Muslim Religious leaders, assorted deposed monarchs, and Muslim extremists seeking a base or refuge, no-one wants the place.
Regards, Uyraell.