@Willy Vereb The Iron Ring is more than just a simple defensive perimeter around the core of Eisenkreis, however, in that it is in some places literally a ring of iron meant to keep the world out of Eisenkreis. Flakk batteries line battlements around the border to cover possible gaps, and highly accurate radar stations watch for anything and everything on approach. This is a nation steeped in deep paranoia regarding the rest of the world, and their religion only perpetuates this almost genetic trait. To them, you all seek to conquer them and destroy their heritage, and so that is why they simply cannot waver in their determination. Kzechverin on the other hand, well... Csilla loves visitors and has never been one to turn down a guest. Not to mention that their military only became armed with rifles in the last century, and was still using spear and plate.And how a "ring of iron" is supposed to keep aircrafts away?
They can be paranoiac all they want. It doesn't change the fact that in WW2 there's no such thing as absolute AA defense.