Don't need nukes.
Start with massive, sustained carpet bombing, 5 times more then the tonnage of bombs we dropped on North Korea and Vietnam combined. Bomb every manmade object, and then all the hills and dales.
FYI during the Korean war we dropped 635,000 pounds of bombs on them. I read that the Norks lost 10% of their total population..
SO as the sustained high volume carpet bombing is going, we send in as big a army as we can. Their orders, are to start at the tip of Kuawait and shot everything that is not in an American. Sure someone will bring up the Brits trying this with their colonies, but they really didn't have the volume of firepower I am talking about. I am talking about levels of death several orders of magnitude beyond the paltry efforts of the Brits.
It would be an interesting sight. The death toll from people escaping the Us death squads would be nearly as high as the death squads themselves as they flee. Eventually they will break out of the Middle East and disperse all over the world, driving up Muslim populations all over but ultimately being too spread out to be a major political influence in any one country.
OR they try to break into the EU by force but get stopped by border nations and the US forces trap and slaughter them like rats caught in a barrel.
Either way, it can be done, with no nukes involved. Ways that will leave us an empty Middle East, ripe for resettlement and massive resource exploitation.
If I were an evil dictator, that is exactly how I would do it. Now, I have to be able to think this way as I write novels. I have to be able to envision the worst possible evils, that way I can write good bad guy.