You can achive this by using the Visitor Groups > Visitor Group Membership criterion.
1. Create a visitor group for identifying the US visitors (using the Time and Place > Geographic location criteria)
2. Create another visitor group and use the Visitor Groups > Visitor Group Membership criteria. Make the setting 'not member of' and select the group.
Or create a visitor group for US and then use fallback content for all others.
How do i do a visitor group "hole world except USA"?
What i want to do is to either show a page or show another page if not that visitor group. I don´t have "not" in the visitor group criterias, then it would be easy.