Maintaining hegemony over the middle East has been a cornerstone of American foreign policy since the end of World War 2. It used to be about oil, and still very much about the pertrodollar, but is also based largely on the belief that should America lose control of the Middle East, the balance of world power will shift to Russia and China, and America's global economoic supremacy will be lost. Iran has long been a thorn in America's side, but Israel and Saudi Arabia are key allies in keeping the Middle east too fucked up to make their own decisions, because if they could they would align with their traditional economic partners in the east.