North Korea has put together a secret army of computer hackers that it uses to disrupt South Korean military options and break into US military computers.
It might seem strange that North Korea has a dedicated cyber-warfare army unit. After all, only a few hundred people in the country even have access to the internet. But the country has worked to establish an elite group of hackers.
North Korean defectors say that the country actively searches for schoolchildren who display mathematical talent, and then trains them up in elite universities to become experts in hacking.