North Korea's Internet went dark for several hours amid rumors of US retaliation over its alleged hacking of a Hollywood studio, just as the pariah state came under attack at the UN over its rights record.
South Korea's nuclear power plant operator launched a two-day drill Monday to test its ability to thwart a cyber attack, after a series of online information leaks by a suspected hacker.
China's foreign minister condemned all forms of "cyber terrorism" in talks with his American counterpart, a statement said Monday, as the US accused Beijing's ally North Korea with being behind a cyber attack on Sony Pictures.
The United States has dismissed a call by North Korea for a joint investigation into the hacking of Sony Pictures and wants China to help block cyber attacks from Pyongyang.
South Korea and Japan on Saturday vowed to work closely with the US to combat cyber crime, after Seoul blamed North Korea for a crippling cyber attack on Sony Pictures.
As one of the world's most impoverished powers, North Korea would struggle to match America's military or economic might, but appears to have settled on a relatively cheap method to torment its foe.
North Korea's UN mission on Friday denied involvement in a cyber attack on Sony Pictures after the US FBI said it had evidence that Pyongyang was behind the hacking.
Film star George Clooney slammed the Hollywood movie industry for failing to stand up against the cyber threats that prompted Sony Pictures to cancel release of the movie "The Interview."
The White House called the cyber-attack on Sony Pictures a serious national security matter Thursday, threatening an "appropriate response" as others pointed the finger at Pyongyang.
Sony Pictures vows it will not be destroyed by a massive cyber attack, a day after hackers promised a big "Christmas gift" for the Hollywood studio.