There's no reference to genocide in the "Trail of Tears" article, so until you find a source that specifically refers to this event as genocidal, I'm afraid it's not relevant. 

 The Cesarani quote addresses "native Americans" but that refers to natives of all the Americas, not just North America or the US. In which case its appropriate location is in the "Americas" section. 

 That just leaves the Stannard quote, which only references the United States in passing, without providing any detail about what genocidal campaigns specifically the US is supposed to have committed. So it's a very vague statement which scarcely justifies a separate section to itself. Apart from which, as I said above Stannard is a controversial scholar whose opinions should be balanced by those who reject his POV. 

 So again let me reiterate - I'm not in any way opposed in principle to a separate section on the US, it just needs to have solid sourcing and to conform with NPOV, that's all. I'm afraid the current version just doesn't meet those requirements.