It’s not in anyone’s interests for Japan to have nuclear weapons. Here's What You Need to Know: Japan’s high population density would mean that the destruction of just a handful of cities could kill or injure the majority of the country’s civilian population. It is perhaps China’s and even North Korea's greatest nightmare: a nuclear-armed Japan. Permanently anchored off the Asian mainland, bristling with nuclear weapons, a nuclear Japan would make China’s security situation much more complex than it is now, and force China to revise both its nuclear doctrine and increase its nuclear arsenal.