RAF aims to cut Islamic State jihadis off from foreign help with campaign of airstrikes

UK participation in Syria likely to focus on the so-called 'Manbij pocket' along the frontier with Turkey where the US is planning intense air strikes

The Royal Air Force will join an offensive to seal off Isil’s last international border and block foreign fighters from travelling to and from the group’s territory.

The US is planning intense air strikes against the “Manbij pocket”, a 60-mile stretch of Isil-controlled Syria along the frontier with Turkey. On its western flank, the so-called 'Marea line', the pocket is under attack by Western-backed Syrian rebel troops. To its east is territory around the town of Kobane, recaptured by Kurdish forces in June.

Denying Isil its only stretch of border will make it significantly harder for young Britons and other westerners to reach the terror group’s so-called state. It will also obstruct terrorists such as Abdelhamid Abaaoud, the leader of the Paris attacks, who travelled back from Isil territory to Paris.