As far as we know I think, it's just the US for now. But if it does well, even just marginally well, I can see them porting it to other countries for one of two reasons. If it does really good, they'll do it for just plain more money. But if it just does okay, there's a chance they may do it in a chance to increase overall sales to keep it going.
Either way, we just have to hope for now. ^_^