During the 2017 presidential campaign, then-candidate Donald Trump was open about his hostility toward Iran and his disdain for the Obama administration’s diplomacy with that country. Since January, the Trump administration has been engaged in an Iran policy review. News reports and leaks suggest the review is highly likely to recommend a more confrontational approach to Iran, whether within the framework of the Iranian nuclear deal or by withdrawing from it. This paper examines the costs of four confrontational policy approaches to Iran: sanctions, regional hostilities, “regime change from...