if ($geoip_country_code = "CU") { return 451; }
if ($geoip_country_code = "IR") { return 451; }
if ($geoip_country_code = "KP") { return 451; }
if ($geoip_country_code = "RU") { return 451; }
if ($geoip_country_code = "SY") { return 451; }
Okay, I know, not perfect, but making a best effort goes a long way.