Divisions among world leaders on Syria have been laid bare in speeches at the UN General Assembly.
The US and France insisted Syria's President Bashar al-Assad must go, but Russia said it would be an "enormous mistake" not to work with him to tackle Islamic State (IS) militants.
However, the US and Russia did hint at compromise. US President Barack Obama said he would work with any nation and Vladimir Putin called for a "broad coalition".
US President Barack Obama and his Russian counterpart Vladimir Putin have met in New York, on the side-lines of the UN General Assembly, after delivering speeches that exposed sharp differences over how to tackle the Syrian crisis.
Speaking after their meeting, Mr Putin said Russia might be willing to join air strikes against the Islamic State group if they were backed by the United Nations. But he ruled out Russian troops ever taking part in a ground operation in Syria.
He said he thought there was a chance for the US and Russia "to work out our differences together".
Russia is considering whether to follow the US and its allies in conducting air strikes against Islamic State (IS) targets, President Vladimir Putin says.
What's the human cost?
More than 250,000 Syrians have been killed and one million injured in four and a half years of armed conflict, which began with anti-government protests before escalating into a full-scale civil war.
And the survivors?
More than 11 million others have been forced from their homes, four million of them abroad, as forces loyal to President Assad and those opposed to his rule battle each other - as well as jihadist militants from IS. Growing numbers of refugees are going to Europe.
How has the world reacted?
Regional and world powers have also been drawn into the conflict. Iran and Russia, along with Lebanon's Hezbollah movement, are propping up the Alawite-led government. Turkey, Saudi Arabia and Qatar are backing the Sunni-dominated opposition, along with the US, UK and...