North Korea is behind the Sony hack, U.S. officials tell NBC News. "We have found linkage to the North Korean government," a U.S. government source said. The officials said they think the hacking attack on Sony executives' emails originated outside North Korea by people acting on orders from Pyongyang. The massive security breach led to the cancellation of the planned Dec. 25 release of "The Interview," a comedy about an assassination attempt on North Korean dictator Kim Jong Un. Referencing the Sony hacks and threats of terrorist attacks on American moviegoers, U.S. officials said the country "can't let this go unanswered." The White House National Security Council said in a statement Wednesday that "the U.S. government is working tirelessly to bring the perpetrators of this attack to justice."