Saudi Arabia has said Iran must accept the removal of President Bashar al - Assad as part of any solution to the conflict in Syria. Saudi Foreign Minister Adel al-Jubeir made the remarks as talks among international foreign ministers on the crisis get under way in Vienna. Iran is for the first time taking part in such talks, which will also include Russia and Turkey. Russia and Iran both support Syrian President Bashar al-Assad. They have both recently stepped up their military role in the conflict. The US, Turkey, Saudi Arabia and other Gulf Arab nations have long insisted Assad cannot play any long-term role in Syria's future. Jubeir said that there was "no doubt" Assad had to go. "He will go either through a political process or he will be removed by force," he said. Meanwhile, Iranian Foreign Minister Mohammad Javad Zarif said that other powers had realized that there was no way reaching "a reasonable solution" to the Syrian conflict without involving Tehran.