So presumably they got it wrong when they gave a Congressional Medal of Honour to George M Cohan in 1949 for writing Over There, with the chorus


Over there, over there
Send the word, send the word over there
That the Yanks are coming, the Yanks are coming
The drums are rum-tumming everywhere

There seem strong grounds to think that the term Yanks in fact originated in the USA, and was exported as. An appropriate term for referring to (US) Americans in general.