North Korea is being implicated in a cyber attack over the July 4 weekend, according to South Korean intelligence officials.
The attack brought down several major American and South Korean Web sites at least temporarily. But other South Korean officials expressed doubt that the North Koreans could carry out such an attack.
Keith Epstein, an investigative reporter for BusinessWeek whose specialty is cyber security, joins Martin Savidge to discuss who is behind the cyber attacks, the consequences of the attacks and how the U.S. can improve cyber security.