From some time around that first simulation (early 1930's), the "plan an attack on Pearl Harbor" problem was in the curriculum of the Japanese naval academy.

From some time around that first simulation (early 1930's), the "plan an attack on Pearl Harbor" problem was in the curriculum of the Japanese naval academy. Hawaii was known to be teeming with Japanese intelligence assets at least since the time of WW1, and its strategic importance had been well known at least since the US had made a point of acquiring the place.