I have a stillborn sub with a similar idea behind it - the Karth. One of a fleet of autonomous warships, the lone (cliche) survivor of the class. It has gone off to make a small empire for itself in a far flung corner of humanspace. Might revive it. Go to Comment
I like the visual of this thing hanging in the sky among the stars.
I find it odd that the US would see the need to nuke Canada, as conventional forces would have a pretty easy time of it, and unless the nukes were tiny, they would be obliterating a good portion of their own population. Detroit, New York state, Oregon, etc. Most of our population is within 100 miles of the states and it would seem like using nukes in a civil war. That and I expect by the timeframe in question, a huge amount of the american water supply would come from Canada.