Prototype already did it.
Also so did Half Life.
And I'm sure someone else but nothing I can think of.
Anyway, if it was actually a good game and wasn't all like "Here's Americans as bad guys, look how controversial I am!", I'd probably play it. But chances are that you aren't actually talking about that, seeing as there are already games that have portrayed some or all of the branches of the US Military as your adversaries.
I'm guessing you're talking about some sort of faceless, mindless evil guys that all wear masks and have PROPERTY OF AMERICA slapped on their foreheads and asses. No, that's dumb and pointless.