The rise of IS in Libya and how the West will respond

The Egyptian air strikes in Libya have opened up a new front in the war against Islamic State (IS) with the extremists there exploiting a power vacuum after the fall of Colonel Gaddafi.

Islamic State are just one of hundreds of militias looking to gain power in a country torn apart from factionalism.

The BBC's James Robbins looks at the background to the rise of IS in Libya.