N. Korea proposes joint probe with US into Sony cyber attack

North Korea called Saturday for a joint investigation with the US into a crippling cyber attack on Sony Pictures, denouncing Washington's "slandering" after President Barack Obama warned Pyongyang of retaliation. The US blames the isolated state for the hacking which prompted the cancellation of the Christmas Day release of "The Interview", a madcap romp about a CIA plot to kill leader Kim Jong-Un which infuriated North Korea. Mark Stroh, a National Security Council spok