I understand your equating these events, but, actually, this is FAR worse. Pearl Harbor was an attack on a legitimate military target, carried out by normal military means. Civilians WERE killed, but they were not the primary targets- the Fleet and supporting installations were the targets. (Don't misunderstand- I'm not giving the Japanese a pass for Pearl Harbor!)
This is the foulest deed ever committed against us as a nation- and I have searched for something remotely comparable. The massacre in the Ardennes during the Battle of the Bulge was as close as I could get- but even there, the atrocity was directed against soldiers. The Bataan Death March? I don't know.