They're one of the most elite fighting groups in the world. They silently slip into hostile countries to train and lead guerilla forces.

The US Army's Special Forces are known to the public as Green Berets — but they call themselves the quiet professionals.

They work in 12-man teams, known as an "A-Team," with each member having a specific job.

The ranking officer is the team leader, the weapons sergeant knows just about every weapon in the world, the communications sergeant tees up ordnance or extract, and the medics can take lives as quickly as saving them.

Here's what they do: