Iran now seen as part of solution to Syria conflict
After long being considered part of the problem, Iran is now being seen as part of the solution - at least when it comes to ending the conflict in Syria.
That became apparent on Tuesday as the United States revealed it had invited Iran to take part in multilateral talks in Vienna on Friday, reversing its long-standing opposition to involving President Bashar al-Assad's closest ally in discussions about his future.
The change in US policy seems to be one of the first political dividends of July's nuclear agreement between Iran and six world powers.
The deal was the result of two years of direct negotiations between Secretary of State John Kerry and his Iranian counterpart Mohammad Javad Zarif, during which there was a need for a great deal of mutual understanding and respect.
Iran has now confirmed that Mr Zarif will travel to Vienna on Thursday for preliminary talks with his Russian counterpart Sergei Lavrov.
He will be accompanied by two deputies, including Hossein Amir-Abdollahian, the foreign ministry's point-man on Arab affairs.
Last Friday, Mr Kerry organised a day of meetings with his Russian, Turkish and Saudi counterparts in the Austrian capital, at which they discussed how to start a political process to end Syria's war.
One topic that would surely have been hard for them to avoid was the fate of the Syrian president.
Russia has always insisted that Mr Assad must be part of any political transition in Syria. But the US, Turkey and Saudi Arabia, as well as Syria's main opposition alliance, have until recently been equally adamant that he must play no role.
While stressing that it is not seeking to keep Mr Assad in power forever, Iran meanwhile believes he needs to continue as president to fight the jihadist group Islamic State (IS) and maintain national unity.
Now with Russia launching an air campaign against Mr Assad's opponents in Syria, and Iran reportedly sending hundreds of combat troops to join assaults on rebel-held areas, the political chessboard has been transformed.
Aside from inviting Iran to attend the talks in Vienna, the US has also said it could live with a political transition in Syria that would leave Mr Assad temporarily in power, potentially removing an obstacle to building international consensus.
For some time, Iran has been pushing a four-point plan for Syria that calls for a ceasefire, followed by the formation of a national unity government, constitutional reforms and, finally, free elections. The plan could, conceivably, now be used as a basis for further discussions.
But perhaps more surprising than the change in US policy, has been Saudi Arabia's acquiescence to Iran's involvement in the talks in Vienna.
According to some reports, only hours before the invitation was sent, King Salman was pleading with Mr Kerry not to do so.
Many in the region see the rivalry between Iran and Saudi Arabia as being at the heart of the deepening conflicts in the Middle East.
Aside from potentially ending the destructive and bloody war in Syria, the talks in Vienna might therefore offer a way to calm that rivalry.