Why not just have Japan lease a few American boomer submarines (with hard-coded missile coordinates) and deploy them in the Pacific. That would give Japan MAD capacity without endangering people on the mainland (a NK first strike couldn't take out the missiles).
Far better would be China stepping in and putting an end to this nonsense before it gets too far out of hand.
this is the softening blow for the "we must re-arm" call and the fear-mongering of the japanese to accept yet another INVASION of an "inferior" people. Pathetic and all the to worry about our future. esp. with japan and the current US on the same page.