Taking a look upon Europe map highlighting NATO members, I saw a rather strange hole in the center:
Both Switzerland and Austria are the only Central European countries that are not NATO members. Switzerland has a long tradition of neutrality (more than 200 years) and this can be a strong argument from not joining NATO.
On the hand, Austria was involved in both World Wars (as Austro-Hungarian Empire in WW1) and, theoretically, it is placed closer to Russia than Spain or France.
Question: Why is Austria virtually the single Central European country that has not joined NATO?