Why does usa has anything to say about bethlehem?

That is a political thing, so anybody's opinion is about as good as anybody else's. There may or may not be a good reason for such a move, but it could as easily be a blunder. In a hundred years somebody might figure out what it was about, and maybe not. For instance, we are still trying to figure out what the civil war was about, and that was a hundred and fifty years ago.