FLYING TIGERS – A small group of misfit American pilots, flying under the Chinese flag, faced the Japanese forces in China before the European conflict broke out.
They were a volunteer force, commanded by Claire Lee Chennault, operating from the Kyedaw airport in Burma. Their shark-faced P-40 fighters remain among the most recognizable aircraft of WWII. http://en.wikipedia.org/wiki/Flying_Tigers
Check out this hair-raising account of how Flying Tiger Tex Hill reacted to a Japanese KI-27 attacking his flight leader over Thailand.