UPDATE 7-U.S. determines N.Korea behind Sony attack as studio pulls movie
December 18, 2014 at 01:13 AM EST
LOS ANGELES, Dec 18 (Reuters) - U.S. investigators have determined North Korea was behind a cyber-attack on Sony Pictures, a U.S. government source said, an unprecedented act that has forced the studio to cancel releasing a comedy about the fictional assassination of North Korea's leader.