Teheran's new status follows nuclear deal with world powers

Iran is taking part in international talks on Syria for the first time this week, giving it a voice in the effort to find a resolution to the more than 4-year-old civil war that has so far defied even the slightest progress toward peace.

A backer of Syrian government, Teheran has been shunned from all previous talks on Syria. Its inclusion now marks recognition by the United States that no discussion on Syria's future can succeed without Iran at the table.