What are the options in fight against IS?

Foreign Secretary Philip Hammond has ruled out working with Syria's President Assad to defeat the threat from Islamic State (IS) militants.

Former head of the Army Lord Dannatt and ex-Foreign Secretary Sir Malcolm Rifkind called for the move following the beheading of US journalist James Foley by IS militants.

The US has described IS, which has seized large swathes of northern Iraq, as the biggest threat it has faced in recent years.

Jeremy Bowen reports on the options in the fight against IS extremists.