Historically the Thai military was supplied by Japan and actually fought a war with the French in 1940-41. Once the Japanese entered the conflict they out-and-out declared war on America and Britain.
But first they fought the Japanese. Thai forces resisted the Japanese landings at Singora and Patani, and inflicted several hundred casualties before being ordered to surrender.
AFAIK, Thai forces never participated in any way in combat against British, American, or Chinese forces, nor did the Allies ever bomb targets in Thailand.