A Promising Moment in Iran The election of Hassan Rowhani as Iran's next president creates an opportunity to move forward on a negotiated agreement to stop Iran's nuclear weapons program and to begin to repair three decades of hostility with the United States. The question is whether Mr. Rowhani and President Obama have the political skill and courage to make it happen. Whether Iran's supreme leader, Ayatollah Ali Khamenei, will allow such an outcome is unknown. But, for whatever reason, he did allow Mr. Rowhani to run in last Friday's election and accepted the results, in which Mr. Rowhani, considered the most moderate of the six candidates, trounced the hard-liners. Mr. Rowhani, a cleric, has deep roots in the conservative establishment, but he is also pragmatic. His campaign pledge to work to end the impasse with the West over the nuclear issue and the sanctions, imposed because of the impasse, resonated with voters fed up with a badly devalued currency, a battered economy and the erosion of rights and freedoms. During his first news conference on Monday, Mr. Rowhani promised to "follow the path of moderation" and allow greater openness over the nuclear program. But he also restated Iran's refusal to halt uranium enrichment as the United Nations Security Council has demanded. Such tough talk is not terribly surprising coming from a new leader who will not be inaugurated until August. Between now and then, American officials, with the other major powers, should be prepared to put forward a comprehensive proposal that aims to halt Iran's activities related to nuclear weapons, gradually lift sanctions and address other issues in which Iran plays a role, like the conflicts in Afghanistan and Syria. President Obama will have to persuade Congressional leaders and Prime Minister Benjamin Netanyahu of Israel that it is necessary and possible to reach a credible deal with Iran. Sanctions were never supposed to be an end in themselves but a tool to facilitate a deal, and Mr. Obama has done a good job of ratcheting up the pressure. With Mr. Rowhani's election, Mr. Obama should respond with more creative diplomatic engagement. It is a chance neither he nor Mr. Rowhani can afford to squander.