Iranian President Hasan Rouhani signaled Iran could ramp up its cooperation with the west over the threat posed by Islamic State if there is a successful conclusion to nuclear talks with six major powers. Speaking at the United Nations General Assembly in New York on Thursday, Mr. Rouhani said the fight against Islamic State should be led by regional players but said a nuclear deal would open the way for international collaboration on the threat. If the nuclear talks succeed, “an entirely different environment will emerge for cooperation at the regional and international levels,” he said. That would allow “greater focus on some very important regional issues—such as combating violence and extremism in the region.” Iran, which is a key ally of the Assad regime in Syria, has criticized the U.S.-led coalition against Sunni […]