Maybe again too. Modern communication could allow for both coordinated widespread first strikes [a lousy idea from the OpSec standpoint, but still do-able] and coordination of followon activities. If such a strike werre to come just before really nasty weather was to hit, especially in the Pacific Northwest and Northeast, the choice for the other side would be either capitulation or starvations and hypothermia.
But you're probably right. When they wargamed something of the saort at the Carlisle Barracks war college, I believe the duration was around 18 months. And involved the use of airpower on city enclaves.
The scenario trigger event was a disputed election, BTW. I've seen notes from the exercise, I'll try to tickle a more comprehensive report out of a couple of my more knowledgable sources. But I'm a little busy kicking tires right now.
-archy-/-