VV,
do not know where you live. But Germany is traditionally a very dangerous place, right in the middle of Europe. Nevertheless I do not have to fear any of our neighbors. Even if we would have no army at all, I doubt that the Austrians or Dutch would invade us. (Well, of course the Dutch do invade us every year, but we do the same to them, and to the Austrians, Italians, Spanish ... ).

I think good diplomacy and being good neighbor is more important than strong military. In fact Germany had the biggest wars when it had the strongets armies.

So small army and a moderate 'my country first' policy, some common sense and humanity - that is all it takes.