Iranian Foreign Minister Mohammad Javad Zarif, who is also Iran’s top nuclear negotiator, waves to his well wishers upon arrival at the Mehrabad airport in Tehran, Iran, from Lausanne, Switzerland, Friday, April 3, 2015. Iran and six world powers reached a preliminary nuclear agreement Thursday outlining commitments by both sides as they work for a comprehensive deal aiming at curbing nuclear activities Tehran could use to make weapons and providing sanctions relief for Iran. (AP Photo/Ebrahim Noroozi)