North Korea said to be building cyber-war arsenal

North Korean hackers are said to be the biggest source of attacks on US military web sites

North Korea is reportedly building a military unit to handle online warfare with the US and South Korea.

A report in South Korean newspaper JoongAng Daily claims that the North Korean People's Army has built a new unit comprising 100 hackers. The hackers are said to be the biggest source of international attacks on US military web sites.

The paper cited government sources in claiming that the hackers are tasked with infiltrating enemy networks and stealing sensitive data. The unit is also thought to be working on malicious programs capable of taking down IT infrastructure in the event of a war.

Cyber attacks against government systems are nothing new, particularly in the US. Most recently, agents in China and Russia were said to be behind a series of attacks on systems which manage the country's power grid. China has since denied its role in the incident.

Online attacks have also proved to be effective in times of armed conflict. Hackers in Russia are thought to have been behind politically motivated attacks that took down government web sites and services in Estonia and Georgia.