"That's certainly possible, but it's also possible that it was some other factor like mechanical failure," said former CIA official Michael Morell.
If it was terrorism, however, Morell said it was likely a bomb placed on the aircraft somewhere along its route, or a person on the plane who intentionally took it down.
What would it mean if it was a bomb, that was placed on the plane in Paris -- the departure airport?
"That would be a very significant development," Morell said. "It says that [ISIS] could now bring it to the United States in a very significant way by doing this exact same thing with a flight to the United States."
Watch the video above to hear what else Morell had to say.