1) Saudi Arabia
Requires all visitors to be sponsored by a legal resident or citizen. Even if you’re sponsored properly, there’s no guarantee that you’ll then be awarded a visa as the application process is highly selective.
Iran doesn’t even have an American Embassy anymore, thanks to the tense Iran hostage situation that occurred there in 1979. If you are able to secure an Iranian visa through the Pakistani embassy in Washington, D.C., you will need to show that you’re traveling with a tour group.