The United States warned Iran on Monday, in both English and Persian, that a preliminary agreement reached two months ago in Switzerland must remain the basis for a final nuclear deal. The warning appeared to reflect concerns among American and European negotiators that Iran’s supreme leader, Ayatollah Ali Khamenei, has been attempting to backtrack on some crucial elements of the April agreement that was forged in Lausanne, the lakeside resort near Geneva. “We do see a path forward to get a comprehensive agreement that meets our bottom lines,” said a senior United States official, who could not be identified under the ground rules for briefing reporters. “This path forward has to be based on the Lausanne parameters. Period.” To reinforce […]