In a WWII documentary, I 'think' it was 'World at War', a very good docu BTW.. It's from the 70's, so some of the info isn't quite correct because of the info learned after the 70's but anyway it is a good docu..
Anyway in the episode about the Japanese surrender they showed the signing on the USS Missouri and MacArthur talking ,etc.. And then they showed some of the representatives of all the countries that were at war with Japan signing the papers.. And one of the Japanese Diplomats who was at the signing on the Missouri said while he was watching all these representatives from the countries Japan was at war with walk up and sign the papers he thought to himself 'what was Japan thinking when we went to war, how could we ever have thought we could have defeated all these countries?
Obviously the US handled 95% of the Pacific War.. But yeah, what was Japan thinking?