During WW2, Thailand declared war on England and US, collaborated with the Japanese in exchange for being able to invade Shan state westwards and north as far as China. Thai soldiers were ordered to fight alongside with Japanese in Malaya and Burma. Thailand was at least "allied with the axis".
After the war they just had to give back the territory and some bags of rice I think.
How come they were let off the hook so easily? Why didn't the allies go harder on their (former) enemy Thailand?
And also the leader Phibun just resigned. (To compare Quisling was shot.) (Personally I would just say that Buddhist mentality does not have death penalty as an easy option.)
My account of the history is highly simplified and may be wrong in some parts. I am a traveler and have seen these areas first hand and heard the stories, so therefore I am interested. I am no historian, I hope possible faults in my account will be corrected.