US President Barack Obama at the G20
US wants the border between the western Turkish town of Kilis and eastern Syrian town of Jarabulus closedGetty Images

The US has urged Turkey to close a stretch of its border running 100 km alongside Syria, which has been used extensively by the Islamic State (Isis) to move its foreign fighters in and out of the war-torn country. It has been estimated that around 30,000 Turkish troops would be required to shut down the stretch of the border.

"The game has changed. Enough is enough! The border needs to be sealed," a senior US government official told the Wall Street Journal. "This is an international threat, and it's all coming out of Syria and it's coming through Turkish territory."

The US wants the border between the western Turkish town of Kilis and eastern Syrian town of Jarabulus closed. It also wants Ankara to keep a close watch on the border between Jarabulus and Cobanbey from where the IS sends most of its weapons and foreign fighters into Syria.

According to The Independent, Turkey has been criticised for its "long-term tolerance of, and possible complicity with" terror groups such as Jabhat al-Nusra Front and Ahrar al-Sham. Moreover, it is reported that Turkey is allowing IS to sell crude oil from its captured oilfield in Syria, giving the terror group much-needed revenue to finance its worldwide terror operations.

"There's no local, capable, motivated force that is prepared to clear this area at this time," a senior US defence official said. "There are two sides to every border. If Turkey is motivated to seal their border, there is nothing that's stopping them from using their conventional forces to do so," the official said.

Meanwhile, a senior Turkish government official said: "Turkey is determined to clean Daesh (Arabic acronym for Islamic State) from the 98 km of border between Kilis and Jarabulus. There is no need to receive any kind of warning or advice from anyone, including our US partners. Just closing down the border would not be enough to solve our problems and would not address Turkey's demands."

Officials have said necessary steps to close Turkey's borders with Syria have been taken but the US believes otherwise. The border situation has become problematic with IS foreign fighters getting trained in Syria and later launching attacks in Western countries. The jihadists have carried out numerous terror attacks on foreign soil, the most notable being the coordinated attacks in Paris which killed 130 people.