The 1989 Malta Summit between President Bush and President Gorbachev put an end to the Cold War. Europe is no longer politically divided, and the world is now undergoing rapid changes. East Asia was also affected by these changes positively, but is still divided into two conflicting ideological blocks. The problem and the danger of nuclear proliferation was vividly shown by the North Korean nuclear crisis in recent years. This paper reviews the issue of nuclear proliferation of the three non-nuclear states in the region, South and North Korea as well as Japan, and deals with the non-introduction of nuclear weapons in the region by the nuclear powers. The prospects of a nuclear-weapons-free zone as well as of a sustainable security environment in East Asia are briefly discussed. Although the solution to the problem of non-proliferation in East Asia depends on economic and political development in the region, non-proliferation needs to be linked to existing global measures with the ultimate goal of global disarmament. The creation of a regional nuclear organization like EURATOM, to be called EATOM or ASIATOM, is proposed. Balance-of-power strategy and defense arrangements with outside powers need to be adjusted. For a sustainable security environment in the region, new thinking about security is much needed and improvement of relations between the countries including North Korea is crucial.