A) No fucking trees for the gooks to hide in.
B) No fucking gooks - just crazy assed rag-heads.
C) Oil, and lots of it, at stake for the invading countries.
D) If we bake the desert with nukes, we lose the option of the oil, unless we're willing to ignore the 'backround raditation' from using post cook out extraction. Aside from the distasteful task of sweeping crispy sand monkeys aside, cleansing the crude will be a real problem.