To non-nuclear state South Korea, the denuclearization of North Korea would be one of its most important national issues. It is also a very important national security issue to Japan and China who are surrounding the Korean Peninsula, and the United States. If, in reality, North Korea becomes a nuclear state, the following astonishing changes regarding the security situation of the Korean Peninsula and its vicinity will occur: (1) non-nuclear state South Korea will become a hostage of nuclear state North Korea; (2) the asymmetry of military power between the two Koreas will make the gap more severe; (3) North Korea may blatantly threat nuclear attack against the U.S. and Japan; (4) The Korean Peninsula, Japan, and the U.S. will be “Within one war theater”, which means the all three nations will be within North Korea nuclear attack’s arms length; (5) South Korea, the U.S., and China will unite slowly in order to achieve a common goal, “North Korea’s denuclearization”; (6) “Nuclear state North Korea” means that more explosive compounds are going to be added to original Northeast warehouse, North Korea. There might be two ways to ensure the survival of South Korea from North Korea’s nuclear weapons. The first way is maintaining peace on the Korean peninsula by “the denuclearization of North Korea” with pulling all strings South Korea can. The second way is to “create a balance of terror”, which is blocking North Korea from using its nuclear weapons. To “the denuclearization of North Korea”, four ways are being discussed: (1) By dialogue and negotiation; (2) By highly strengthening sanctions on North Korea; (3) By Preemptive attack; (4) By qualitative change of North Korean regime or by removal of the regime. Likewise, “to create a balance of terror”, four ways are being discussed; (1) Relocating the U.S. nuclear umbrella; (2) Strengthening and improving the US combined defense system; (3) Strengthening South Korea and China’s strategic cooperation; (4) Developing South Korea’s own nuclear weapons.