Friday’s news conference at the Department of Defense came before the FBI blamed North Korea for the attack on Sony, but Pentagon spokesman John Kirby did address issues surrounding cyber defense and the sticky question of what exactly is an “act of war” on the Internet.

U.S. Department of Defense spokesman John Kirby speaks at a news conference on December 19, 2014. (Photo: DOD)

“I’m not able to lay out in any specificity for you what would be or wouldn’t be an act of war in the cyber domain. It’s not like there is a demarkation line that exists in some sort of fixed space on what is or isn’t,” he said.

“The cyber domain remains challenging, it remains very fluid. Part of the reason why it’s such a challenging domain for us is because there aren’t internationally accepted norms and protocols, and that’s something that we here in the Defense Department have been certainly arguing for.”