As for 'Operation Storm', you first Nuke it, then blast it from orbit, and only then attack it with troops. What is this fortress made of? There is no known cladding or armor that will take the nuke alone, and if it survived that what would survive an orbital bombardment then a plasma bombardment and then need the troops? Plasma, by definition, is heated to the same temperature as the surface of the sun, so again I ask, what is it made of, since nothing known to man would survive sitting in the corona of our own own sun? And it is not the first, but the third weapon used?
That's the point of operation Storm. To make sure that no enemy is alive. Vader wants to wipe out the Nomads, so they stop their raids against the Empire.
So he uses every weapon possible to be 100% sure that no one can survive.
As to what the Fort is made of, you will see in a few Chapters. I have already planned a Chapter about the Empire sending some spies in the Nomads capital.