North Korea's Internet crashed Monday only days after the U.S. warned of retaliation for the Sony hacking scandal.
North Korea experts and web specialists said the massive outage to the North's online connections could be the result of a cyber attack by an outside country or a defensive action by the North Koreans to take down their systems to guard against a retaliatory attack.
U.S. officials denied involvement in the North Korean blackout that followed President Obama's Dec. 19 warning of a "proportional response" to the attack on Sony Pictures Entertainment over the comedy movie "The Interview."
Last Friday, the FBI blamed the Sony hacking on North Korea over the movie, whose plot involves the assassination of North Korean leader Kim Jong-un.
Sony pulled the movie from release after a group calling itself "Guardians of Peace," which claimed to be the hackers, issued threats against theaters planning to show the movie.
North Korea experts also noted that the North's main link to the Internet runs through the northern Chinese city of Shenyang. China, the North's only major ally, has come under pressure from the U.S. to rein in its neighbor.
"For the past 24 hours North Korea's connectivity to the outside world has been progressively getting degraded to the point now that they are totally offline," said Doug Madory, director of Internet analysis at New Hampshire-based Dyn Research.
"There's either a benign explanation -- their routers are perhaps having a software glitch, that's possible. It also seems possible that somebody can be directing some sort of an attack against them and they're having trouble staying online," Madory said.
Adam Segal, a China specialist at the Council on Foreign Relations, said the problem could be internal. He noted that North Korea's Internet went down for several days last year. "It could also be North Korea pulling into a shell" to prevent an attack, Segal said in a conference call with reporters.
Scott Snyder, a Korea specialist at the Council on Foreign Relations, noted that "the North Koreans distanced themselves from the Guardians of Peace at the same time that they praised their actions."
North Korea has also issued threats to attack the White House if the U.S. responds to the hacking attack on Sony. North Korea "has clear evidence that the U.S. administration was deeply involved in the making of such a dishonest reactionary movie," the North's Korean Central News Agency said Monday.
-- Richard Sisk can be reached at firstname.lastname@example.org