Kerry in Moscow to push Syria peace plan

US Secretary of State John Kerry has arrived in Moscow, where a meeting with President Vladimir Putin could decide the fate of Syrian peace talks.

Kerry first held talks with his usual sparring partner, Foreign Minister Sergei Lavrov, but the success of his trip will depend on the rare Kremlin meeting with Putin.

"I think the world benefits when powerful nations with a long history with each other have the ability to be able to find the common ground," Kerry said as he sat down with Lavrov.

"And today I hope we will be able to find some common ground."

Kerry and Lavrov have a reputation as friends despite the ups and downs of the US-Russian relationship, but the pair were grave and business-like as their teams sat down in a Moscow mansion.

I think the world benefits when powerful nations with a long history with each other have the ability to be able to find the common ground - John Kerry

Washington is relying on the Kremlin to drag Russian ally Bashar al-Assad to the table for talks with his rebel opponents on ending Syria's vicious four-and-a-half-year civil war.

US ally Saudi Arabia is putting together the coalition that would negotiate on behalf of the rebels, with a view to first agreeing a ceasefire and then launching a political dialogue.

Looming over the effort to end the bloody conflict is the threat posed by the Islamic State group to spread the carnage beyond Syria's borders.

Kerry said Russia and the United States were agreed on the need to fight the Islamic State group, despite differences on the peace process and Assad's eventual fate.

The hope is that if the regime and the rebels can agree a truce then they, Russia and a US-led coalition of Western and Arab allies can focus their fire on IS.

Washington and Moscow are the key powers in the process, leading talks through the 17-nation International Syria Support Group in cooperation with the United Nations.

Washington and the UN envoy for Syria, Staffan de Mistura, want to hold the next round of ISSG talks on Friday in New York, but Moscow has so far refused to confirm the date.

Kerry called Lavrov the "co-convenor" of the talks and thanked him for his efforts "to lead us up now hopefully to getting to New York and building on the progress that's been made".

'Agree to disagree'

Ties have also been strained over the crisis in Ukraine, but US diplomats said they would not be drawn into bargaining with Russia over the sanctions it imposed over Moscow's interference there.

Russia, which has dispatched air and naval forces to Syria to shore up Assad's regime, has agreed to help Washington pursue the peace plan.

In talks last month in Vienna, Kerry "agreed to disagree" with Moscow about Assad's fate. Moscow says it is for Syrian voters to tell him when to go.

The US believes Assad's brutal crackdown on opposition protesters in March 2011 triggered a civil war that has killed more than 250,000 and driven recruits to the Islamic State group which profited from the chaos.

America's regional allies, led by Saudi Arabia, are even more emphatic in declaring that Assad must go, demanding he step down as soon as peace talks begin.

Opposition leaders met last week in Riyadh and began the process of choosing their negotiating team - but also repeated their demand that Assad step down immediately.

Meanwhile, back in Washington, US President Barack Obama voiced fresh determination to destroy the Islamic State group, vowing to kill the group's leaders and win back territory in the Middle East.

On the ground in Syria, a military source said government troops recaptured a military airport and town east of Damascus, more than three years after they were overrun by rebel groups.