U.S. says Bashar al-Assad's fate to be decided in global talks

"I do not foresee a situation in which we can end the civil war n Syria while Assad remains in power", Obama said. They joined Russian war planes based at the Hemeimeem air base in Syria's province of Latakia. "It was very fruitful, because the Russians understand very well this region, because they have historical relations, they have embassies, they have all kinds of necessary relations and means to play a role", he said. "What is happening in Syria will continue to take place and nothing will change at this pace", Anas said. Like Russian Federation, Iran has provided generous military support to Damascus and is standing by Assad. "Assad has created the state in his image", said Landis.

Meanwhile, both Italy and Britain's foreign ministers both spoke supportively Thursday of Russia's efforts in fighting IS, signaling a Western softening to Russia's involvement. Forging an alliance with the West to fight IS would offer Putin a chance to raise Russia's global clout and prestige and to fix relations that were shattered by the Ukraine crisis.

"In order for this to be successful, at a few point the Russians and the Iranians are going to have to make a fundamental decision", Mr Obama said. The country also has suffered increasing casualties from the war.

Earlier Russian Foreign Affairs Minister Laurent Fabius told France Inter radio "We think they are honest and we must bring together all our forces" and Russia's Sergei Lavrov said Moscow could work with the US-led anti-IS coalition as long as it respects Syria's sovereignty.

"It's often the case that in the wake of a major event, particularly a major tragedy, there is room to start talking about things and get past all the posturing", Daniel Benjamin, a former State Department official under Obama and now director of Dartmouth College's Dickey Center for worldwide Understanding.

"Syria has been a Pyrrhic victory for Iran", he said. "Their image in the Sunni Arab world will likely be tainted for decades to come".

The United States and its allies argue it will be impossible for the two-year plan hashed out in Vienna, which would see a transitional government set up, a new constitution written in six months and election 18 months later, to work without clarity on when Assad will go.

The conflict began in March 2011 with peaceful protests against Assad and evolved into a civil war that has sucked in world powers, most recently France as it retaliates against the massacre in Paris by bombing Islamic State's stronghold in Raqqa.

But Assad is not likely to leave willingly anytime soon.

Embattled Syrian leader Bashar al-Assad's fate will be decided in global talks in the coming weeks, the United States said on Thursday, brushing off his rejection of moves to sideline him from peace talks.

"Nothing can start before defeating the terrorists who occupy parts of Syria", he said, adding that if Syria's people want presidential elections "there will be no red line" against holding them.