Some genius (and I say genius since these things usually happen with just a single planner) realized that he had to use the existing resources to acquire oil in just about 30 days, so some things were possible and others weren't.
There was little margin for error so the planner simply chopped off all the "nice to have" stuff ~ leaving himself with an air attack on Pearl Harbor, main battle groups to Singapore, Philippines, Malaysia, Indonesia, and as soon as that was clear the tankers were sent to the oil fields ~
Later on, in the exuberance of victory somebody else sent units to the Aleutians, Sakhalin and beyond, and to screw around in the South Pacific.
They ended up with a great deal of their ground combat units bogged down on islands we never attacked nor needed to attack. The Japanese were forced to supply those troops on those islands with ships that were probably needed to support activity in China. The Chinese venture continued, and then got worse when the US used safe areas in China as landing pads for bombings of the Japanese Home islands.
One thing led to the next and the US ended up with the whole enchilada!
If the Japanese could have counted on a 6 month supply of oil back in 1941, they'd spent more time planning the attack because that was going to happen anyway whether we cut off their oil or kept sending.
All the theories that place the blame on FDR necessarily assume the Japanese didn't know how to plan major war movements ~ and that's just crazy talk!
Exactly so —the Pacific War was very much about oil.
In fact as a Navy guy very much aware that oil was the lifeblood of a modern Navy, Yamamoto had done a big paper at Harvard regarding the US oil industry —he even had a convertible and spent a good deal of time driving around the USA checking out refineries and so on.
And that is why he paid a maximum of attention to speedily gaining control and re-establishing productive oil-rich places like the Dutch East Indies, etc.
Oil, oil, oil, oil, oil —the economy and Navy need it.
And...I don’t have a problem with it —in fact I think very little has changed.
As we will soon see in the Spraties, etc.