To contain a post-accord Iran, the United States will need not only to bolster Saudi Arabia, but Egypt and Turkey as well. Egypt’s security services under de facto military strongman Abdel Fattah el-Sisi are already quietly allied with the Israeli security services in Gaza, Sinai, and elsewhere. America requires a strong Egypt — democratic or not — as a regional anti-Iran ally to bolster Saudi Arabia. While Turkey under President Recep Tayyip Erdogan is not normally viewed as a pro-American country, a strong Turkey in and of itself also helps balance against Iranian power. The jostling among these geographically and historically fortunate powers for regional dominance will define the new post-imperial order.

A new American president in 2017 may seek to reinstate Western imperial influence — calling it by another name, of course. But he or she will be constrained by the very collapse of central authority across the Middle East that began with the fall of Saddam Hussein and continued through the post-Arab Spring years. Strong Arab dictatorships across the region were convenient to American interests, since they provided a single address in each country for America to go to in the event of regional crises. But now there is much less of that. In several countries, there is simply no one in charge to whom we can bring our concerns. Chaos is not only a security and humanitarian problem, but a severe impediment to American power projection.

Thus, the near-term and perhaps middle-term future of the Middle East will likely be grim. The Sunni Islamic State will now fight Iran’s Shiite militias, just as Saddam’s Sunni Iraq fought Ayatollah Ruhollah Khomeini’s Shiite Iran in the 1980-88 Iraq-Iran War. That war, going on as long as it did, represented in part the deliberate decision of the Reagan administration not to intervene — another example of weak imperial authority, though a successful one, since it allowed Reagan to concentrate on Europe and help end the Cold War.