I was 6 years old when WWII broke out, living in a rural farming area. My father's critical skills brought him to downtown Los Angeles, and us to a suburb. Fortunately there were some vacant lots, and neighbors worked together to plant gardens, raise goats and chickens, etc. Fuel, rubber and many primary source foods were very scarce. I can remember my father "rebuilding my shoes" They had to be stretched as I was growing. He resoled his and my mothers. Vacations? 4 families all pool the gas coupons and ride in several cars for a local lake and that was it.
Todays younger generation does not have the skills, nor the fortitude to endure deprivation. They will not fight, they don't believe in "America and our values". Some older folks will step up and run our industries. But the overall effect is that we could not ramp up to the scales as wwII. So much of our military equipment is computer (ie chip) operated. and we just don't have that capacity currently. John Deere and Caterpillar will crank out what is needed, and probably can ramp up. The auto manufacturers to some extent. Ships? We are down to only two or three really effective shipyards for the building or supply of the massive navy which would be necessary for a War in the Pacific. Air craft, not too far off either. Ships and planes are so much different and complex with multiple source supply of parts.
The war will escalate very rapidly and hypersonic weapons may well be first strike. If we can get second strike in, it is a game changed. If not--we are overcome. The grid, water supply and transport will grind to a halt except for military needs. We spend a lot on the military, but I question what we really get. There is a lot of graft in the supply lines.
I am not sure how much occupation would be necessary. We already have plenty of politicians who would love to lick the boots of other communist leaders. Those of us who are patriots will be the gorilla force attacking our own leaders who surrender to the enemy. Are there enough patriots in the National Guards, Reserves, and law enforcement ranks? I don't know--but it may well be a civil war, rather than minimal occupation. For example, I would rank our state of Florida as those who would resist. But not Calif. New York, Oregon, or Washington. Those who control the utilities, and health care control the population!