In 2008, Barack Obama was the only presidential candidate with the foresight and fortitude to openly acknowledge the need to engage America’s adversaries diplomatically. Iran was at the top of his list. Four years later, the imperative has only grown, but the logic behind Obama’s thinking has not changed: the U.S. has much to gain and little to lose by abandoning its policies of the past three decades—including the revised Bush policy that became Obama’s policy—and instead beginning a real effort to establish working relations with Iran. The enmity will not be undone over the course of a few meetings. Success will only come if diplomats place a premium on patience and long-term progress rather than quick fixes aimed at appeasing domestic political constituencies. Few argue against the need to try, and no realistic alternative better serves U.S. national security imperatives. Diplomacy with Iran is a marathon, not a sprint.