From the end of Chapter 3 ("Magic") of Roberta Wohlstetter's Pearl Harbor:

The point is that the puzzle is never complete. The signals that the local commanders later argued were muffled and fraught with uncertainty are the ones they viewed before the event. The signals that seem to stand out and scream of the impending catastrophe are the ones learned about only after the event, when they appear stripped of other possible meanings.

All decisions are made in the face of uncertainty, even those that depend simply on an understanding of natural phenomena. But decisions based on reading the intentions of others, and in particular, the intentions of an enemy, are especially difficult. These intentions are complicated and shifting, and subject to change between the time the intent is signalized and the time of the intended act. Sometimes they are also deliberately obscured, or invented to mislead, as in the case of bluffing. At least in reading natural phenomena, we have Albert Einstein's famous assurance that God is subtle but not plain mean. The same cannot be said for the enemy.

^z - 2017-11-01