Thailand in World War II officially adopted a position of
neutrality until it was
invaded by Japan in December 1941 which led to a armistice and, later, the military alliance treaty between Thailand and the
Japanese Empire. At the start of the
Pacific War, the
Japanese Empire pressured the Thai government to allow the passage of Japanese troops to invade British-held
Malaya and
Burma. The Thai government under
Plaek Phibunsongkhram (known simply as Phibun) considered it preferable to co-operate with the Japanese rather than fight them, since Japan promised to help Thailand regain some of the indochinese territories (in today's Laos and Cambodia) which had been lost to France.
Axis-aligned Thailand declared war on the United States and Britain and annexed territories in neighbouring countries, expanding to the north, south, and east, gaining a border with
China near
Kengtung.
[1]
Thailand retained control of its armed forces and internal affairs. The Japanese policy on Thailand differed from their relationship with the puppet state of
Manchukuo. Japan intended bilateral relationships similar to those between
Nazi Germany and
Finland,
Bulgaria, and
Romania.
[2] However Thailand at that time has been labelled by both the Japanese and the
Allies as the
"Italy of Asia"