Iran’s President Hassan Rouhani (R) walks with Oman’s Sultan Qaboos bin Said ahead of a meeting in Tehran in this August 25, 2013 photo provided by the Iranian state news agency (IRNA). Oman’s Sultan Qaboos on Sunday began the first visit to Iran by a foreign leader since moderate President Rouhani took office and Iranian media said his trip might be an effort to mediate between Tehran and Washington. Picture taken August 25, 2013. REUTERS/IRNA/Handout via Reuters (IRAN – Tags: POLITICS) ATTENTION EDITORS – THIS IMAGE WAS PROVIDED BY A THIRD PARTY. NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS