As far as I know, there has never been a serious plan by any nation for the invasion and occupation of the mainland US. In both World Wars Germany (and in WWII Japan) limited their warplans to establishing naval supremacy and possibly bombarding coastal cities. I don't think the USSR had a plan to occupy the US, just as the US did not have a plan for the occupation of Russia (at least, I think they didn't, I'd be happy to discover otherwise).

The closest I can come up with is a speculative plan commissioned by Kaiser Wilhelm in the early 1900s, which would have included an occupation of some North Eastern cities such as New York, and a march to DC in order to force the US into a peace favourable to Germany. The occupations would be very short term so I don't think they accounted for a militia forming. The entirety of the general staff thought it was a ridiculous idea and only made the plan because the Kaiser ordered them to. This information came from http://www.zeit.de/2002/20/In_New_York_wird_die_groesste_Panik_ausbrechen My German is nitch sehr gut so I couldn't go into much detail, sorry about that.

This is about as close as I could find to a serious proposal to invade the US. As far as I know, no others exist, and honestly I would be extremely surprised if they did. I know this wasn't the answer you were looking for, but I hope it was at least informative.