Quite possibly one of the most expensive ways to advertise you're not allowed nukes...
I would say it is more of a case that their enemies are much closer than Americas are or Russias are so a missile with a range of 3,500km is good enough, but they want to obliterate their enemies with as many warheads as they can make and deliver.
These warheads will not be directed against military targets... they will be city killers with the objective to wipe out a large portion of the civilian population of their enemy countries... Japan and South Korea no doubt....