EU's Ashton in Iran Says Final Nuclear Deal 'Challenging'
Description:EU foreign policy chief Catherine Ashton said on Sunday there is no guarantee of a successful long-term nuclear agreement with Iran. She was in Tehran for a two-day visit, the first by an EU foreign policy chief since 2008. Iran and six world powers, represented by Ashton, are seeking a long-lasting agreement over Tehran's disputed nuclear program. A deal would help put an end to years of hostility between Iran and the West.(1:37)