Barack Obama entered the presidency with a clear plan for engaging Iran. Rather than building on past rhetoric and emphasizing Iran’s "misbehavior," he opted for a new approach. In a speech marking Iran’s new year, he praised Iran’s rich history, then reached out directly to the country's new president, Hassan Rouhani. The approach did not show immediate results, but the two countries, along with European powers, Russia, and China, began to negotiate over Iran’s nuclear program – a key issue for the relationship since the 1990s. The P5+1 talks (and secret US–Iran meetings) slowly began to turn the tide. The JCPOA finally came into being, representing a significant diplomatic achievement. Through it would prove to be short-lived, the Iran deal demonstrated that progress could be achieved. After forty years of near-constant enmity, the two countries appeared to be on the verge of détente. When Donald Trump unilaterally pulled the US out of the deal, these hopes were again dashed. But lessons from the negotiations remain for future policymakers hoping to resolve this most confounding of global issues.