TEHRAN: Iran said Wednesday it will attend the international talks on Syria's future later this week in Vienna, following an invitation from the Russian envoy that would mark Tehran's first appearance at such a gathering.

The invitation to the talks came after the United States declared itself ready to engage long-time foe Iran if it might help halt Syria's four-year civil war.

Iran is a key ally of Syrian President Bashar Assad and has provided his government with military and political backing for years. Tehran admits that its Revolutionary Guard officers are on the ground in Syria in an advisory role, but denies the presence of any combat troops in the country.

Iranian state TV quoted Foreign Ministry spokeswoman, Marzieh Afkham, as saying Wednesday that Foreign Minister Mohammad Javad Zarif will attend the talks. It didn't provide details but said Zarif discussed the Syrian crisis with his Russian counterpart, Sergey Lavrov, on Tuesday night and Wednesday morning.

The TV also said Deputy Foreign Ministers Hossein Amir Abdollahian, Abbas Araghchi and Majid Takht-e-Ravanchi would accompany Zarif on the trip.

"We believe the solution for Syria is a political solution. Americans and foreign players in Syria have no choice but to accept the realities in Syria," Abdollahian told state TV Wednesday. "Assad ... has the necessary readiness for talks with insurgents who are committed to a political path."

Iran's semi-official ISNA news agency also quoted the foreign ministry spokeswoman as saying the Islamic Republic would attend. Earlier in the day, she said Tehran was considering whether to join the gathering in Vienna.

U.S. Secretary of State John Kerry, Russia's Lavrov and several top European and Arab diplomats, including those from Saudi Arabia and Qatar, will be attending — a familiar cast that up to now has not included any Iranian representatives. Kerry departs for the Austrian capital on Wednesday.

Iran's attendance could be a game-changer. Iran has backed Assad's government throughout the conflict and the Syrian opposition may balk at Iran's inclusion in any discussions on what a post-Assad Syria should look like. Tehran's attendance would also mean that traditional Iran-Saudi regional rivalries could surface at the negotiating table.

But all previous international efforts have failed to stop the war, now in its fifth year with over 250,000 dead and millions displaced from the conflict.

Washington is trying to unite all sides with influence in the Arab country around a common vision of a peaceful, secular and pluralistic Syria governed with the consent of its people.

Beyond Iran, this week's gathering will expand to include countries such as Britain, France, Germany, Jordan and the United Arab Emirates. Egypt's Foreign Minister Sameh Shukry also said Wednesday he would attend.

Iran's supreme leader, Ayatollah Ali Khamenei, had ruled out new negotiations with Washington after the United States and five other nations clinched a long-term nuclear agreement in July. But Iran clearly has a stake in Syria's future, as Assad's government has helped the Iranians exert dominance over nearby Lebanon and threaten Israel through their proxy, Hezbollah.

Amid all the talking, Syria's fighting goes on.

Since last month, Russia has launched hundreds of airstrikes targeting what it says are the Islamic State and other terrorist groups. The Obama administration, NATO and others say most of the bombs are landing on moderate rebel militias, some backed by the CIA.

Meanwhile, violence continues to rage between Syria's rebel groups and the Islamic State, and in the Kurdish region in northern Syria, even drawing in Turkey.