Well, I’m not trying to make a point about Montana specifically, more about ballistic missiles generally.
In fact I think they have essentially zero accuracy until well after they get past the boost phase and get into the cruise - straight line phase.
Speaking to the scenario, Minot is very close to the geographic center of North America, which is just down the road. Might not be perfect, but it’s as good as it gets. You know what they say about “close” (It only counts with horseshoes, hand grenades, and atom bombs...)