US Secretary of State John Kerry on Tuesday, 17 November, said the United States was starting an operation with Turkey to finish securing the northern Syrian border, an area Islamic State (IS) militants have used as a lucrative smuggling route.

"The entire border of northern Syria — 75% of it has now been shut off. And we are entering an operation with the Turks to shut off the other remaining 98 km," he said in an interview with CNN.

Kerry arrived in Paris on Monday, 16 November, to pay respects to the victims of last Friday's militant attacks, which killed 129 people.

The area on the Turkey-Syria border where the operations would take place is now controlled by radical Islamists. The US and Turkey hope that by sweeping Isis, also frequently called "Daesh", from that border zone, they can deprive it of a smuggling route that has seen its ranks swell with foreign fighters and coffers boosted by illicit trade.

Under a long-discussed joint US-Turkish plan, moderate Syrian rebels trained by the US army would be expected to fight Isis on the ground and help coordinate airstrikes by the US coalition, launched from Turkish air bases, under the strategy drawn up by Washington and Ankara.

Diplomats familiar with the plans have said cutting off one of Isis' lifelines could be a game-changer in that corner of Syria's complex war. The core of the rebels, who are less than 60 in number, would be highly equipped and be able to call in close air support when needed, they say.

"We are in a common struggle with the US against Daesh, and in the coming days some steps will be taken together," said a Turkish official.

But, there are major challenges as well.

Turkey is distrustful of the Syrian Kurdish YPG militia, which has proved a useful US ally in fighting Islamic State. It controls adjacent territory on the eastern side of the Euphrates River, just across from Karkamis and the jihadist-held town of Jarablus. Ankara wants it to advance no further and considers the Euphrates a red line not to be crossed.

Earlier, after meetings with French President Francois Hollande and Foreign Minister Laurent Fabius in Paris, Kerry said increased coordination with Russia in the fight against Isis militants would require progress in the political process to end the Syrian war.

He said agreements reached last week at Vienna peace talks on Syria meant the country could be "weeks away, conceivably, of a big transition".

He referred to independently conducted US and Russian air strikes in Syria.

"At the moment, it's matter of making certain we are hitting the right targets and not running any risk of conflict among ourselves," said Kerry. "But it's possible that if the political process moves more rapidly, there could be greater level of exchange of information and so forth."

"Iran, Russia ready for a ceasefire, the United States ready for ceasefire," he said.

"But there needs to be legitimacy to this process. So, the faster Russia and Iran give life to this process, the faster the violence can taper down and we can isolate Daesh and al Nusra, and begin to do what our strategy has always set out to do," he added.

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