Vienna Summit: Rival Powers Begin Talks on Syria Crisis

Foreign ministers from the United States, Russia, Turkey, Saudi Arabia, Iran and several other countries will meet on Friday in the Austrian capital of Vienna, in what marks a major diplomatic push to end the Syrian civil war.

Neither the Syrian government, nor members of the country's opposition groups have been invited to the meeting. Some of the countries attending the summit, including regional rivals Turkey and Saudi Arabia, have made it clear that they do not want President Bashar al-Assad to play a part in a transition government.

The meeting will be the first since the start of the Syrian conflict to include Iran. Iran, the main regional backer of Assad, accepted an invitation to participate earlier this week. Foreign Minister Javad Zarif will advocate for the inclusion of the Syrian president in the transition to peace. Russia, who has been supporting Damascus with airstrikes targeting militant Islamist and opposition groups for nearly four weeks, is also likely to push for Assad to be included in the process.

All of the powers meeting at the summit have launched airstrikes against various targets in Syria during the conflict, with the exception of Iran, which has reportedly sent ground troops to the country.

George Sabra, a member of the Syrian National Coalition, told Reuters that the failure to invite the Syrian opposition showed a "lack of seriousness" in the aim of the talks.

U.S. Secretary of State John Kerry met with his Saudi, Turkish, Iranian and Russian counterparts on Thursday, in anticipation of Friday's meeting, AFP reports.

Early statements from some of the diplomats expected at the discussion table on Friday already set the stage for a heated discussion.

Zarif said "a reasonable solution" on Syria could not be reached without Tehran's presence, despite Syrian opposition expressing their strong criticism of including the Iranian side.

Saudi Foreign Minister Adel al-Jubeir told the BBC that Riyadh would continue to advocate for Assad to leave power "either through a political process or he will be removed by force." Syria's information minister, Omran al-Zoubi, meanwhile told Syrian Arab News Agency that Jubeir should "keep his mouth closed and keep his country out of a matter that is none of his business."

Relations between Iran and Saudi Arabia are also likely to prove particularly problematic. The two countries are engaged in a regional power struggle, backing different sides in the wars in both Syria and Yemen.

Top diplomats from the U.K., France, Germany, Egypt, Lebanon and other EU and Middle Eastern states are also expected to attend the meeting on Friday.