Yeah the fire nation has way more similarities to Imperial Japan than anyone else. Island nation industrializes before their neighbours and just starts taking over. Style of dress, the archesticure, the names of the characters, all give a Japan vibe way more than an American vibe. But maybe drinking tea in a ceremonial fashion is something that’s part of American culture that I wasn’t aware of.
But currently the US is protecting global trade from pirates and sending weapons to democracies defending themselves from authoritarian psychopaths, which to some people is exactly how the Fire Nation behaved in Avatar I guess.