Battle for Sinjar: 'There are snipers. We need to be careful'

Kurdish forces have launched what they say is a major offensive to drive militants of so-called Islamic State out of the town of Sinjar, in the north-west of Iraq.

Sinjar was captured in August last year by the militants who attacked the mainly Yazidi population, killing many of the men and enslaving women and children.

Jim Muir reports from the front line.