US, Russia Achieve 'Clarity' on Path to New Syria Ceasefire: Kerry

"Today I can say that we achieved clarity on the path forward" towards a revamped cessation to the fighting, Kerry told reporters alongside his Russian counterpart Sergei Lavrov after marathon talks.

Lavrov added that "substantial agreements had been reached", while noting that "some things need to be finalized".

Kerry stressed that the two sides were not prepared to make a definitive announcement, but said US and Russian technical experts would continue to meet in Geneva in the coming days to hammer out a set of unresolved issues, AFP reported.

"We are working on those issues," Washington's top envoy said. "Neither of us is (ready) to make an announcement that is predicated by failure - we don't want to have a deal for the sake of a deal."

Kerry claimed the near total collapse of a previous ceasefire agreed earlier this year was linked to the failure to respond to violations.

Successive rounds of international negotiations have failed to end a conflict that has killed more than 290,000 people and forced millions from their homes.

Moscow and Washington support different sides in the war, which erupted in 2011 when the country became engulfed in deadly foreign-backed militancy.

Friday's meeting came as the conflict became further complicated by Ankara's decision this week to send tanks into Syria.

Turkish-backed militants have seized the Syrian border town of Jarabulus from Daesh (ISIL) terrorists. But Turkish forces have also shelled a US-backed Syrian Kurdish militia.

Turkey sees the PYD and YPG militias as terror groups bent on carving out an autonomous region in Syria and acting as the Syrian branch of its own outlawed Kurdish PKK.

Ankara's hostility to the YPG also puts it at loggerheads with its NATO ally the United States, which works with the group on the ground.

The Russian air force has been carrying out airstrikes in Syria since September last year against terrorist targets at the request of the Syrian government.
The US and Russia have a common foe in Daesh, and they have been in contact on efforts to establish military cooperation against the group.

As a possible sign of increasing cooperation, Moscow vowed on Thursday to work with the US on a response after a UN investigation found that the Syrian government had carried out at least two chemical attacks.

The two countries co-chair a UN-backed humanitarian taskforce for Syria, which has been struggling to ensure access for desperately-needed aid across the country.

Aleppo, Syria's second city, has emerged as a top concern for negotiators.

Russia last week gave its blessing to a long-demanded 48-hour pause in fighting in the city to allow in aid, but de Mistura on Thursday accused other unspecified parties of dragging their feet.