Anyone have a simple way to switch on US vs non-US traffic on a WP post for what Advertisements to show? I have one affiliate offer that pays well, but only on U.S. traffic. Unlike other affiliate companies, they do not kick the clicker to an offer available for their country though instead they throw a 404 error...

The two methods that come to mind are on load vs on click, just don't know how to switch on the country of origin for what Ad to show or destination URL to serve (either will work).