[IMHO]

I really have a hard time seeing a loosly organized bunch of individuals project even defensive naval power, widespread air defense or a multi-divisional armored formation.

The Japanese never invaded the US mainland due to the fact that "there is a rifle behind every blade of grass" (paraphrased quote by some Japanese Admiral). This worked as well for the Swiss in WWII, and the minutemen in the Revolution

[Axenolith]

Yamamoto made that statement, and it was true relative to that time. As for the Swiss, they afford an extremely low cost\benefit ratio for a potential attacker with respect to potential casualties and economic resources.

I'm not sure that scenario would hold against an aggressive nuclear armed China, and a battleship and aircraft carrier free US in 1941 would similarly not have detered Japan from at least beginning to sieze US territory, starting in Alaska and continuing south (which they did temporarily with Attu and Kiska).