korea is responsible for the crippling attack on sony pictures, there s increasing focus on a mysterious unit called bureau 121. experts say north korea withheld resources from its own citizens to build up this unit to carry out cyberattacks. for morors let s get to kyung lah live from seoul. what do we know, kyung? well alisyn, think of them as the shadow warriors, and their battleground is cyberspace, they re placed around the world, taking their orders from pyongyang, with one common goal these warriors aim to disrupt western interests. north korean soldiers, a technicolor parading force against the west. on state-run television a near ridiculous bravado of the military. but there are unseen soldiers in kim jong-un s cyberwar versus the west. they have no face, and only known by a number, bureau 121.