The sudden rise of Islamic State in June shocked the world. It now controls a swathe of the desert in Syria and Iraq and has declared a caliphate. Iraq’s second city, Mosul, has fallen to the militants and they are menacing the capital, Baghdad. Western powers and their Gulf Arab allies have responded with war planes and bombs. The American general in charge of the campaign says it is buying time for the Iraqi Army to regroup and counter attack. But what would a long-term plan to defeat Islamic State look like? The Inquiry’s panel of experts have some thought-provoking ideas.