Taking a look at the following map of Europe highlighting NATO members, I saw a rather strange hole in the center. Switzerland, Austria & Liechtenstein 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 for not joining NATO. On the other hand, Austria was involved in both World Wars (as the 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?