United States authorities say they’re certain that North Korea is behind the attack on Sony, but they haven’t provided any proof to back their claims, except for the fact that the attackers used IP addresses “exclusively used by the North Koreans.” Everyone agrees that attribution is tricky. Some believe US authorities are jumping to conclusions, but others say the FBI surely has other evidence, which they might never share with the public, to back their claims. This topic will be debated by a panel of experts and moderated by The Wall Street Journal's Danny Yadron.