I don't know anything about their motivation having been taught WWII in an American classroom, but it seems like such a terrible strategic move. We were not involved in WWII at that point and as far as I know there was no definitive plan to join since Congress was debating over it. So what was their incentive? Did the Japanese anticipate the US joining? Also, the fact that they didn't have planes advanced enough to return home after the attack makes it seem even more of a mistake to attack.
Hi, I've answered this question before: https://www.reddit.com/r/AskHistorians/comments/3dxlh4/what_did_japan_hope_to_accomplish_by_attacking/
I'm curious as to what you mean by this, though -- could you clarify?
they didn't have planes advanced enough to return home after the attack
The Japanese planes involved in the attack (other than the 29 destroyed in the attack) returned to their aircraft carriers and thence back to Japan. Are you maybe thinking of the Japanese midget submarines, that were intended to not return?