Islamic State conflict: How does it make its money?
The self-styled Islamic State raises millions of dollars every single month - which is why oil fields controlled by the fighters have been the main target of UK strikes in Syria so far.
The hope is that by destroying some of them it will be harder for the group to raise money to pay their fighters and buy weapons.
So how has the militant group already managed to raise billions of pounds?
Video produced by Adam Eley.
04 Dec 2015