The United States would like to compartmentalize the Iran nuclear deal, continuing to oppose Iran’s subversion in the Middle East and hostility to Israel while assuring regional allies that the deal will not lead to a broader U.S.-Iran rapprochement. Yet if the deal is to be a force for stability, it requires winning over fearful U.S. allies and reducing Iran’s rivalry with the Gulf states. Afshon Ostovar warns that Iran and the Gulf states must temper their ambitions and seek compromise to prevent sectarian-driven conflict from drowning the region.