The North Korean Internet was completely down for around 9 hours, before connections were brought back online on Tuesday.

The nation is currently embroiled in a cybersecurity confrontation with the U.S. due to the Sony Pictures hack, which the White House has blamed on Kim Jong-un’s government. No one has yet claimed responsibility for the attack on North Korea, and U.S. officials have denied any involvement.

North Korea's Internet Outage: Who Was Responsible?

Internet security company Dyn Research has been monitoring the situation, and stated that the connectivity problems could be due to technical issues, but were also consistent with the effects of a cyber attack. Speaking out on the Sony Pictures hack, President Obama promised a “proportional response.”

Who was responsible for North Korea’s internet outage?

Dyn Research has claimed that the blackout could have been due to a Distributed Denial of Service (DDoS) attack. Bringing down a network as small as North Korea’s in such a way would not be difficult, and an individual hacker would certainly be capable of such an action.

Matthew Prince, CEO of U.S.-based CloudFlare, said that the resumption of Internet service “is pretty good evidence that the outage wasn’t caused by a state-sponsored attack, otherwise it’d likely still be down for the count.”

China, through which the vast majority of North Korean traffic passes, has denied that it was responsible for the outage, calling such speculation “irresponsible.” China is an important regional ally of North Korea, and the U.S. government has asked for its help in dealing with the Sony hack.

U.S.-China cooperation

The U.S. has appealed to China to identify any North Korean hackers working in China, and also asked them to shut down servers and routers which serve its neighbor and ally. Such actions are necessary to show North Korea that cyberattacks on the U.S. will not be tolerated.

The Chinese Foreign Ministry has reiterated its opposition to cyberattacks of any kind, but refused to acknowledge North Korean responsibility for the Sony hack due to an apparent lack of proof.

The internet security community remains divided as to whether North Korea was responsible for the Sony hack, and details are even thinner on the ground concerning the outage in the secretive nation. The White House has yet to officially act on the matter, with President Obama stating that the U.S. would respond “in a place and time and manner that we choose.”