Diplomacy has so far been a total failure during a civil war that has divided the Middle East, killed a quarter of a million people, driven more than 10 million from their homes and left large swathes of Syria in the hands of Islamic State militants. The mainly Sunni Muslim Arab states that support the insurgency against President Bashar al-Assad have had virtually no productive contact with either Damascus or Assad's main backers, Shi'ite Iran and Russia. Syria's foreign minister met his Omani counterpart in Muscat on Thursday to discuss the crisis, fresh from a visit to Iran.