US secretary of state John Kerry said on Tuesday the United States is starting an operation with Turkey to finish securing the northern Syrian border, an area that ISIS militants have used as a lucrative smuggling route.

“The entire border of northern Syria — 75 per cent of it has now been shut off. And we are entering an operation with the Turks to shut off the other remaining 98 km (61 miles),” he said in an interview with CNN. Mr Kerry arrived in Paris on Monday to pay respects to victims of Friday’s militant attacks that killed 129 people.

The area where the operations would take place is now controlled by the radical Islamists. The United States and Turkey hope that by sweeping ISIS from that border zone they can deprive it of a smuggling route which has seen its ranks swell with foreign fighters and its 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.

Meanwhile, the United States continues to look for opportunities to strike at the ISIS but needs its European allies to make bolder moves to defeat the group militarily, US defence secretary Ash Carter said on Monday.

In comments during his first public appearance sin-ce attacks in Paris on Friday, Mr Carter said the attacks had “galvanised” France into taking bolder action against ISIS and cooperating further with the United States, and that he hoped it would have the same effect on other Europ-ean partners. “We’re looking to do more, we’re looking for every opportunity we can to get in there and go at ISIS, but we need others to get in the game as well,” Mr Carter said.