From the fine article - I believe the new weapons would be of limited number, and only launched from Vanderburg (as compared to North Dakota). And the Russians (and Chinese?) would have inspection rights at Vandenburg to assure that the warheads were only non-nukes.
Indeed, the v of the 1/2 mv ^2 equation would be so enormous for the impact that I don't imagine they need explosives at all. Let the physics to the heavy lifting.
As to fighter plane range - there is also planning for the strike with AAA suppression and fighter cover. Call it 24 to 48 hours. With this thing, if you see a rocket on the NK launch pad at breakfast, it is gone by lunchtime.