WASHINGTON - North Korea's Internet was on the fritz for a second day Tuesday. But the US is staying silent on whether it launched a cyber attack as payback for the hacking of Sony Pictures.
And in the murky world of cyber security, experts say there are several plausible scenarios for why North Korea suddenly went dark, stressing it's impossible to know exactly what happened.
Did the US launch a cyber attack on North Korea?
While some have been quick to make the link between Pyongyang's connectivity woes and a pledge by US President Barack Obama to retaliate for last month's Sony hack, many analysts aren't convinced.
"It's unlikely, if only because we can't make decisions that fast," said cyber expert James Lewis, a senior fellow with the Center for Strategic and International Studies (CSIS).
Washington has asked for help from Pyongyang's ally Beijing to rein the North's cyber activities, so "monkeying" around with Internet services linked to China would not make much sense, he told AFP.
It was also a pretty unsophisticated attack, if it was an attack, said Doug Madory, director of Internet Analysis with Dyn Research, the US monitoring company which broke the story of Pyongyang's Internet problems.
"We don't have direct evidence of some kind of cyber attack, but it would be consistent with that," he told AFP. Given the low-level of sophistication "the cast of characters that could have pulled this off is immense." "If a nation state such as the US wanted to take North Korea off, I'm not sure it would have taken them 12 hours." For its part, the Obama administration is dodging questions and refusing to publicly outline any measures it takes against Pyongyang.
So is China the main suspect?
It's certainly near the top of the list. North Korea only has connections to four Internet networks and they all run through China, operated by a single provider, China Unicom.
"That's a fragile state of affairs," said Jim Cowie, chief scientist with Dyn Research.
China has been increasingly frustrated by the erratic behaviour of North Korea's new young leader, Kim Jong-Un.
Simply pulling the plug on its Internet would send a strong signal of its displeasure, while at the same time shoring up ties with the United States which has indicted five Chinese military officers for hacking into US companies to steal trade secrets.
On the other hand, simply pulling a plug would not have caused the "hours and hours" of instability in the networks, which first alerted Dyn Research to the problem.