Kim Jung Un’s North Korea has declared itself as a nuclear power and continues to develop nuclear programs. The fourth nuclear test on January 6, 2016, and the subsequent missile test firing on February 7, 2017 has brought about a global response resulting in the toughest UN resolution 2270 to impose sanctions on North Korea. South Korea’s most impending security interest is to defend itself against North Korea’s aggression. The Park Geun Hye government has pursued the so-called the Trustpolitik, which made room for engaging with North Korea when progress is made in the measures of confidence building. However, since the fourth nuclear test, the South Korean government has been focused upon enhancing deterrence and strengthening sanctions, multilaterally and bilaterally. South Korea should be prepared to cope with: 1) all-out nuclear attack from North Korea; 2) asymmetric escalation based on nuclear capability; 3) increased propensity for conventional provocation stemming from stability-instability paradox; and 4) other asymmetric attacks using various terrorist measures.