Set Custom Taxonomy to Entire Site Programatically

I got it to work by registering a custom taxonomy…

add_action( 'init', 'create_country_tax' );
function create_country_tax() {
    $userInfo = geoip_detect2_get_info_from_current_ip();
    $country = $userInfo->country->isoCode;
    register_taxonomy($country,'country');
}

and then calling taxonomy_exists('US').