North Korea had shown its nuclear capability through three nuclear tests. This threatens peace and stability in the Korean Peninsula and Northeast Asia. When North Korea increases nuclear warheads with its miniaturization and has transportation measure, it is to intimidate neighboring countries directly, being under situation to be received nuclear horror and menace. If a nuclear-armed DPRK is not tolerable to Japan, a nuclear-armed Japan would be not likewise tolerable to its neighboring countries. The neighboring countries, which possess nuclear science and technology, under the logic of deterrence and mutual action may make progress nuclear armament in opposition to North Korean nuclear threat. It is neither desired nor happened. In order not to realize that possibility, international society should make efforts. Even though the US and PRC have been playing for the positive role with patience for North Korean nuclear nonproliferation, they have to contribute for North Korean nuclear abandonment. This is to keep the Non-Proliferation Treaty system and contribute to stop the nuclear domino in Northeast Asia.