Iran has announced it will attend international talks on the Syrian crisis being held in Vienna.
It will be the first time Tehran – an ally of Syrian President Bashar al-Assad – has been present.
The foreign ministers of the US,Russia, Saudi Arabia and Turkey are also involved.
Egypt and Iraq have also agreed to attend.
Russia and Iran insist President Assad must be part of any political transition.
But the US insists that this must be short and he must step down promptly.