As a Brazilian I can say that it's a very debated topic, at least here in Brazil. Some people get offended by only the (US)Americans being called this way, like it's "unfair".

Everyone who live in the countinent named America can be called American, but lenguages are dynamic, casted by its usage. So, since it's practically stated that people who live in the North America are Americans, I don't see the harm on using it.

Although I strongly believe that in an official or academic paper you should not use simply American, but North Americans or US residents. Anyway, I think it should be specified.

Picture, for example, a South American reading your work. Is there a chance he or she get offended? Then avoid it.

First: Rob, thank you. Hug me.

Ok, now I'll read the rest of the text and the comments.