Four-Way Syria Talks Aim to Bridge Differences as Iran Set to Enter

Key nations backing Syria's warring sides will seek to thrash out differences at talks Thursday as Iran readies to make its debut at international negotiations on ending the four-year conflict.

Russia, the United States, Saudi Arabia and Turkey, the four major powers meeting in Vienna, support opposite sides in a war the U.S.'s top diplomat has described as "hell".

The conflict, which has claimed around a quarter of a million lives, showed no signs of abating as Russia apparently carried out its first strikes in Syria's south, a monitor said Thursday.

It is the second round of talks in less than a week between Russia -- a supporter of Syrian President Bashar Assad -- and the United States, Saudi Arabia and Turkey, which all back rebel groups.

"The only solution for finding an end to the Syrian crisis is to put as many parties as possible around the table," a senior European diplomat said.

"In doing that, the opening of negotiations -- even if it's just a start -- is a good thing."

The gathering comes ahead of a wider pivotal meeting of regional players on Friday when Iranian Foreign Minister Mohammad Javad Zarif will join representatives from Britain, Egypt, France, Germany, Italy, Lebanon and the European Union.

It will be the first time the major players in the conflict are in the same room but there has been no mention of either the Syrian government or the opposition joining.

Britain's Foreign Office said the United Arab Emirates, Qatar, and Jordan will also attend Friday.

The inclusion of Iran -- another key Assad backer -- in this week's meetings marks a crucial shift after Tehran was excluded from earlier talks, mainly because of opposition from Washington and Riyadh.

U.S. Secretary of State John Kerry, who arrived in Vienna early on Thursday, cautioned that this week's talks would not secure an immediate political solution, but represented the best hope available.

"While finding a way forward on Syria will not be easy -- it's not going to be automatic -- it is the most promising opportunity for a political opening we have seen," Kerry said just before he set off for Austria.

"The challenge that we face in Syria today is nothing less than to chart a course out of hell," he added.

Kerry was also to meet Austrian Foreign Minister Sebastian Kurz and the U.N.'s envoy on Syria, Staffan de Mistura, on Thursday in a bid to possibly set up additional meetings with key players later in the day.

Washington is at loggerheads with Moscow over Syria, accusing Russian forces of concentrating their air campaign there on moderate opposition groups opposed to Assad's rule.

Moscow says its bombing campaign is targeting Islamic State jihadists and also other "terrorist" groups.

But Kerry has stressed that the U.S. and Russia also shared "common ground", arguing that both want "a united, secular Syria" in which citizens can choose their own leader through elections.

After months of failure, efforts to find a breakthrough have gained pace as hundreds of thousands of Syrians have fled their shattered country.

Serious divisions remain over when or whether Assad should step down -- and four-way Russia-U.S.-Saudi-Turkey talks in Vienna last Friday failed to make a breakthrough.

On one side, Russia and Iran are backing Assad's forces on the ground and say Damascus must be helped to defeat "terrorism" before a political process can take shape.

On the other, the U.S. and its key regional allies Turkey and Saudi Arabia are supporting groups fighting Assad and insist he must go.

French Foreign Minister Laurent Fabius said Wednesday that France and its allies had agreed on the need for a "precise timetable" for Assad's departure.

The dynamic in the Syrian conflict shifted after Russia launched its air campaign on September 30, claiming it was targeting Islamic State (IS) fighters.

Russia appears to have carried out strikes in southern Syria's Daraa province for the first time in an apparent expansion of its aerial campaign, the Syrian Observatory for Human Rights monitor said on Thursday.

Iran is also believed to have sent thousands of troops and Hizbullah fighters to support Assad's forces.

But the U.S. believes the fighters will struggle to defend Assad for long, which is why Tehran has forced to engage diplomatically.

The Pentagon has announced plans to step up attacks on IS jihadists in Syria and Iraq, including even possible "direct action on the ground".

More than 250,000 people have died in Syria's war since it began in March 2011 following a bloody crackdown on protests against Assad's rule.

Doctors without Borders warned Thursday that a "significant increase" of air strikes on Syrian hospitals had killed at least 35 patients and medical staff recently, without specifying who was behind bombings.