* For Poland in the Soviet-Polish War (1919-21).
* For the Whites in the Russian Civil War (1917-22).
* For China in the Second Sino-Japanese War (1937-45).
Yes, an old American tradition.
Russian airmen fought against the USA during Vietnman and Korea. But, they were the good guys.. I guess.
Some American Black Pilots flew for Ethiopia when Mussolini invaded. They were the first to fight fascists, flying old ships, some from WW I, against the best the Italians had. I always thought that story would make a great movie.