Japan is already in the position of having nuclear-tipped ICBMs essentially "whenever it wants". The conservative time period from decision to arm with nuclear

Japan is already in the position of having nuclear-tipped ICBMs essentially "whenever it wants". The conservative time period from decision to arm with nuclear weapons and having ICBMs with usable nuclear warheads was estimated by (public) CIA documents at 1 year. That's less than it takes to make a new power plant.