North Korea back online after internet shutdown

North Korea has returned online after experiencing several hours of internet outages on Monday. This is coming just a few days after US President Barack Obama vowed to respond to a major cyber attack on SonyPictures, which he blamed on Pyongyang.

Both countries have been involved a row following a cyber attack on US-based Sony Entertainment. The hackers said they carried out the attack because of a comedy drama, The Interview, from the studio about a fictional assassination of North Korean leader Kim Jong Un.

It is unclear at this point what caused the shutdown. The spokeswoman for the State Department, Marie Harf said she cannot confirm whether North Korea had lost access to the Internet due to a cyberattack.

"We aren't going to discuss ... publicly, operational details about the possible response options or comment on those kind of reports in anyway except to say that as we implement our responses, some will be seen, some may not be seen," she said.

North Korea has earlier denied any involvement in the cyber attack on Sony Pictures but praised the hack as a "righteous deed" and threatened to hit back against any US retaliation, citing the White House and the Pentagon as its possible targets.