Paul Kennedy, professor of history at Yale University and author of The Rise and Fall of the Great Powers, predicts that “South Korea cannot possibly be the Switzerland of East Asia because, geographically and geopolitically, it is not like, or in the same place as, the Swiss Federation." in The New York Times on 27 August 2010. This pessimistic forecast reflects his realist interpretation of world politics that the future of South Korea, for all its prosperity, would be veiled in a fog mingled with “a strange of mixture of economic optimism and physical insecurity." We need to admit Kennedy's gloomy prospect for the future of South Korea as a grave warning that its physical vulnerability to national security and defence can be the fatal Achilles' tendon shattering its dream of unceasing national development. Are there any prescriptions for the geographical and geopolitical vulnerability to South Korea's national security and defence? The author suggests that South Korea need to learn valuable lessons from the so-called “hedgehog national defence" of Switzerland, which frustrated the invasion scheme of Hitler's Wehrmacht to end the existence of neutral Switzerland in World War Ⅱ. The paper begins with the historical examination of the hedgehog national defence of Switzerland which led to escape Nazi occupation while other neighboring European nations succumbed. The paper continues to discuss the three secrets of the Swiss hedgehog national defence such as constitutional patriotism, armed neutrality and integrated civil-military relations and their relevance to the current national security and defence of South Korea. Finally, the paper concludes with some policy suggestions for both refurbishing the grassroots administrative system and strengthening the homeland reserve forces at the level of Eup-Myeon-Dong in South Korea based on the three secrets of Swiss hedgehog defence.