Iran is a foreign-policy priority for the administration. Trump withdrew from the 2015 nuclear deal among Iran, the U.S., and five other world powers, and now wants Iran to come to the table for fresh negotiations in pursuit of a stricter agreement. Trump’s advisers may also be aiming for more: regime change in Tehran. Their instrument of choice is maximum economic pressure—ever-tightening sanctions that will cut Iran off from the world economy. But Iran has so far refused to budge; it has responded by escalating tensions in the Persian Gulf and threatening to resume full-scale nuclear activity.