Would you say, then, that the attack on the USS Cole was not a "terrorist" attack because it was on a legitimate military target?
The point is, I think, that the attack on Pearl Harbor was a government sanctioned event, by troops under a defined hierarchy, wearing visible uniforms.
It was an act of war, not terrorism.
Unless towels on the head is a definable uniform that separates the perpetrators into an easily definable sanctioned military organization, then the attack on the USS Cole was an act of terrorism. Just my opinion.