[en] Neighbouring countries surrounding Korean Peninsula, which are the US, China, Russia, Japan and Taiwan, are all the nuclear countries. Some of the neighbouring countries, the US, China and Russia, are nuclear weapon states as well as the nuclear peaceful use countries. Other countries, Japan and Taiwan are not the nuclear weapon states but keep the high level of nuclear energy technologies. Meanwhile, Korea is recognized as the country of which peaceful activities for nuclear energy utilization are much more vigorous. Therefore, Korean national policies on politics, diplomacy and defense may be highly possible to be impacted on by nuclear policies of the neighbouring countries. This study defined the neighbouring countries as those which have politically or economically a direct or indirect relationship with Korea. And then, nuclear capabilities of the neighbouring countries and their impacts on our national security were analyzed in terms of nuclear techniques. Defensive response is technically most probable measure against nuclear threats and terrors. It include the establishment of national nuclear emergency response system as well as the development of environmental radiation protection, decontamination and environment recovering technology. Finally, it was suggested that a cooperation agency of enhancing the development of dual-use technologies be located at a science and technology complex