3:15 PM PT -- U.S. investigators have determined the Sony hackers were working with, or for, North Korea ... according to CNN.

Sony has pulled the plug on the XMAS release of "The Interview," after a number of theater chains bailed.

TMZ broke the story Thursday morning ... Sony execs felt their out was if distributors yanked the film because of safety concerns. That would give Sony an out without directly bending to the hackers.