South Korean computer researchers (left) check the computer servers of the Korean Broadcasting System as a South Korean police officer from Digital Forensic Investigation watches at the Cyber Terror Response Center at the National Police Agency in Seoul on Thursday, March 21, 2013. (AP Photo/Lee Jin-man)
South Korean computer researchers (left) check the computer servers of the Korean Broadcasting System as a South Korean police officer from Digital Forensic Investigation watches at the Cyber Terror Response Center at the National Police Agency in Seoul on Thursday, March 21, 2013. (AP Photo/Lee Jin-man)
South Korean computer researchers (left) check the computer servers of the Korean Broadcasting System as a South Korean police officer from Digital Forensic Investigation watches at the Cyber Terror Response Center at the National Police Agency in Seoul on Thursday, March 21, 2013. (AP Photo/Lee Jin-man)
U.S. Air Force Airman First Class, Lee Simpson from Sportanburg, S.C., mans a machine gun atop a humvee, with South Korean soldiers during a joint military drill between South Korea and the United States near the Osan U.S. Air Base in Pyeongtaek, south of Seoul, South Korea, Thursday, March 14, 2013. (AP Photo/Lee Jin-man)
U.S. Air Force Airman First Class, Lee Simpson from Sportanburg, S.C., mans a machine gun atop a humvee, with South Korean soldiers during a joint military drill between South Korea and the United States near the Osan U.S. Air Base in Pyeongtaek, south of Seoul, South Korea, Thursday, March 14, 2013. (AP Photo/Lee Jin-man)
Mock South Korean missiles are silhouetted at the War Memorial of Korea museum in Seoul on Sunday, Oct. 7, 2012. South Korea said the United States has agreed to allow it to develop longer-range missiles that could strike all of North Korea. (AP Photo/Lee Jin-man)
A girl looks at a display on the impact of supposed nuclear attack on South Korea at the Korea War Memorial Museum in Seoul, on Tuesday, Jan. 29, 2013. North Korea appears all set to detonate an atomic device, but confirming the explosion when it takes place will be virtually impossible for outsiders, specialists said Tuesday. (AP Photo/Lee Jin-man)
A girl looks at a display on the impact of supposed nuclear attack on South Korea at the Korea War Memorial Museum in Seoul, on Tuesday, Jan. 29, 2013. North Korea appears all set to detonate an atomic device, but confirming the explosion when it takes place will be virtually impossible for outsiders, specialists said Tuesday. (AP Photo/Lee Jin-man)
** FILE ** In this Sept. 28, 2012, file photo, Google executive chairman Eric Schmidt arrives for a seminar at Yonsei University in Seoul, South Korea. Schmidt is preparing to travel to one of the last frontiers of cyberspace: North Korea. (AP Photo/Lee Jin-man, File)
