In the CBI theater, what role did Thailand act ? She joined Japan against Vichy France in Indochina to take back lost lands. When Japan was about to lose in 1944, Thailand distanced Japan and joined the US-led Allies. How would this acceptable to both sides of the conflict. Japan needs an Ally in southeast Asia; only Thailand was independently powerful enough to be useful to Japan. IJ army and aircraft used airstrips and bases. Thailand during the early 19th century reigns of Rama I and Rama II were powerful enough to interfere in Vietnam politics and civil combat so Thailand was reasonably strong in its national power.However this Thai power might not be a characteristics of hers: When France suffered during the turmoil of Louis XVI and the Revolution, she was still powerful enough on one hand to support the founder of the Nguyen dynasty. So even under revolution, France was still powerful to fend against forces in colonies, which was not surprising -- the rising general Napoleon defeated coalition forces. More than 100 years later, Why did British and France still see Thailand as a buffer ? Why can they dissect Thailand to their benefits ?
For information, E. Bruce Reynolds wrote two books about Siam Japan attachment to each other during ww2. http://www.amazon.com/E.-Bruce-Reynolds/e/B001HPBZYC