You would think that an overall strategy would be the starting point for an AI. I'm playing a USSR game and have seen some weird things happening. Including the US bypassing Japan/Europe -twice- and just invading Nationalist China (Japanese Puppet) and Communist China (USSR Puppet). Also, the USA DOW-ed me as the USSR, even though I had a massive army and it was just a month or two after I defeated Germany and the Allies defeated Italy thereby concluding war on the Axis powers. It is now two years later and the US still hasn't attacked me directly, although it did mess up Commie China pretty good until I decided to help out. Furthermore, they have researched all nuclear techs, but haven't built a single nuclear reactor, allowing me to build nukes earlier than them despite starting later.
If it is really the case that the AI can determine which beaches to land on, but then invades the wrong country, then what the heck is up with that? That makes no sense...