Meet the parajumpers risking their lives to rescue seriously wounded soldiers from the Afghan battlefield.
When soldiers are injured on the frontline in Afghanistan, it's the para jumpers that have to go in by helicopter and rescue them from the battlefield.
It's a nightmare job - retrieving horribly injured colleagues, while coming under more attack themselves.
Sean Smith from The Guardian spent a month and a half in Afghanistan, seeing first-hand what they have to go through and getting a no holds barred look at life on the frontline.
He also followed United States marines on foot patrol, in 55 degree heat and under frequent attack; they're trying to reach Pakistan to secure the border, but it's taken them a year to move just 20 kilometres.
